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text Spencer Fleury: Okay, you guys are set.
Bogdan Onac: Okay, thank you.
Henry Schwarcz: My name is Henry Schwarcz. I am a professor of geology at McMaster University in Hamilton, Ontario, Canada.
BO: And Im interviewing Professor Schwarcz. [I am] Bogdan Onac. [We are at] USF. Today is January 22, 2008, and its my second interview with a monster of the karst sciencethere was one guy that we just lost a few years ago, Professor [Marian] Pulina from Poland. He used to say, We are mammoths, you are just small popples. You have to grow up to get mammoth like we are. So, Henry is one of these mammoths that have done a lot of things for karst. So, we will have a kind of small discussion and try to figure out how he got involved in caves andwell, some of the achievements, because he carries with him lots of very important achievements.
HS: Okay, thank you. So, Im going to start out by talking about my early history as a student, because everything leads up to the point where I became interested in karst. I was originally born and raised in the city of Chicago in Illinois, and I went to the University of Chicago in the late 1940s and early fifties [1950s], which if anyone knows anything about isotopes will note that this was the time when Harold Urey, a Nobel Prize winning chemist, was developing the theory of stable isotope geochemistry, though he couldnt possibly have known how far it was going to go. And Sam Epstein was a postdoctoral fellow in his lab, and a few other people whose names are probably less familiar in the karst community. Harmon Craig was also a graduate student at that time. And Cesare Emiliani, a very important figure, was a student of Ureys; and I knew all these people more or less, though I didnt, by any means, meet them all while I was at the University of Chicago in the first instance.
Now, I did my undergraduate degree at Chicago, which in those days was a liberal arts degree, and so really didnt have the opportunity to learn anything about anything isotopic for sure. In the last year I was there I became a student in the department of geology, and then I met Sam Epstein just before he was on his way to Caltech; and as it happened when I graduated from Chicago and then after I finished my one year of graduate work in geology, I also went to Caltech as a graduate student. And there I was sitting at the feet of Sam Epstein, and not very far away down the coast in La Jolla was Harold Urey and Harmon Craig. And I was sort of surrounded by stable isotopes, but not actually personally involved with them in a research sense because I chose instead to learn regular geology, mineralogy, petrology and metamorphic petrology so that my graduate degreemy Ph.D.was on metamorphic petrology of silicate rocks. Nothing whatsoever to do with isotopes and certainly nothing to do with karst: but, on the other hand, the seeds were being planted in my head for something along these lines because I was, as I say, surrounded by these great fathers of the discipline.
Eventually, I graduated from Caltech and went toback to the University of Chicago as a postdoctoral fellow. Now, one of the people who had been a graduate student at Caltech with me was Bob Clayton, and he became a professor, first at Penn State and then at Chicago, and I went to be his post-doc. In fact, I was his first post-doc, and I then really discovered stable isotopes for myself because of my Ph.D.my postdoctoral fellowship was on the study of stable isotopes applied to, still, metamorphic rocks, not having to do with karst; but as it turned out, I was working on metamorphic carbonates and so I began to move sort of in that direction. And all the time that I was at Chicago I was also absorbing a lot of other isotopic information because I was in the Enrico Fermi Institute for Nuclear Studies, which is a seething hotbed of isotopic research of all different kinds. So, inevitably it was likely that I was going to come back. You know, if you think about it, the ideas that Ive been pursuing for the rest of my life were stimulated by being in that kind of a very rich environment, first Caltech and then Chicago.
So, in 1962 I left Chicago and took up a position at McMaster University. Now, why did I go to McMaster University? It seems like an odd place to goa university in a small town in southern Ontario not far from Toronto. Maybe one of the reasonsyou could imagine one of the reasons was because Bob Clayton, the guy who I had just been working with, was born and raised in Hamilton, but thats actually completely irrelevant. In fact, he didnt even realize I was applying for a job there until after I got it. And the reason I went there [was] because of a man named Harry Thode. Thode is certainly not a very well knownnot so well known a name in isotope geochemistry as he should be. He was a giant in the field of sulfur isotope geochemistry. He reallyin the North America, at leasthe was the guy who really created the field of the study of stable isotopes of sulfur in biological processes in ore deposits and every other kind of environment. And so being that there was a stable isotope research program there, it seemed like a good place to go since I had just come from a stable isotope post-doc, and also, I was going to be a professor in the department of geology.
Well, at the same time when I came to McMaster, I also met the professors in the geography departmentsome of them, anyway, and one of these, I thinkIm not sure if he wasI think he wasnt there yet, but he arrived a couple of years after I got therewas Derek Ford. And Derek and I became casual acquaintances, shall I saywe became good friends in a way having nothing to do with research.
Ah! (catching a breath) So, now the story gets a lot more complicated because
BO: Yeah. Moving to the karst now.
HS: Now we have to get into karst. Okay.
BO: Yeah. Derek was coming from Cambridge, or from?
HS: Well, Derek was coming from Oxford.
BO: Oxford. Yeah.
HS: And he had done his degree with Margaret Sweeting on studying the karst of his native habitat; and youll be hearing from Derek on this series, I gather, because he is going to be recording not long after me, and hell talk about the Mendips and his Ph.D. research and so on.
But at any rate, I knew nothing what so ever about karst and about stalagmites and about anything of this sort. However, I did know about stable isotopes. After arriving at McMaster, I wasI should have continued studying the isotopes in silicate rocks, which is what I was had been working on at Chicago, but it turns out thats a little practically more difficult than working on carbonates, since to react a carbonate you just need to drop a crystal material in phosphoric acid and analyze the gas that comes off, whereas for silicates you have to have this fiendishly dangerous materialbromine pentafluoride or fluorine gas or something like that, which scared me a lot. I had done it a little bit at Chicago, but I would prefer not to have to do it. So, I realized there were a lot of interesting problems still in carbonates, so I stayed with the carbonate problem. And then Derek pointed out to me that he had been working for a couple of years at that point about on these interesting looking objects made of calcium carbonate, which were called stalagmites.
Well, I told him that I didnt know anything about the subject, but Id look it up. And so I went off to the library to learn something about stalagmites and the first thing I found was an article in the then quite young publication Earth and Planetary Science LettersI think it was in there, anywayby a couple of Germans. I cant actually remember their names now, but they had done a study of the oxygen isotopes in stalagmites, and they had shown very clearly that stalagmites were totally useless objects to measure isotopes on.
BO: I think it was [Johannes] Geiss?
HS: No, it wasnt Geiss. It wasoh, God, what was it?
BO: It doesnt matter, really.
BO: I just try to figure out
HS: I cant remember, anyway, but the point is that they had done this analysis on stalagmites, which came from the mouths of cavessome which were very easy for them to collect. And they showed that they were highly fractionated, that the isotopic composition varied all over the place and didnt make any sense at all, and so they were useless material to work on. And so I told Derek this and he said, Well, too bad. I guess we cant do anything with the isotopes. But at the same time, I remembered from my days working inwell, I better go back and explain something else about my history.
I was also involved with people who were doing radioactive counting experiments while I was at the University of Chicago. I wasnt actually doing the work myself, but I became very familiar with the kinds of equipment which was needed. Back in those days, the subject of low level radioactivity was very hotactually thats kind of a pun, actually, because people were very concerned about environmental contamination coming from nuclear weapons testing. And so, techniques for measuring very low concentrations of radio isotopes by various kinds of counting devices were being rapidly developed in the U.S. laboratories. In fact, the center of this work was in Oak Ridge, Tennessee, which was where the original atomic weapons production had gone on, and there was an Oak RidgeOak RidgeI forget what it was calledTennelec. I remember it was one of the companiesit was Tennessee Electric Company. It was one of the people [entities] who used to make
BO: The first alpha spectrometer.
HS: Yeah, alpha spectrometers. Okay. So the idea was, you could count radioactivity using a solid state detector, and in particular, it seems that there was a way of determining the level of radioactivity in speleothemsor, lets say, samples which contain low concentrations of uraniumby placing a purified sample in front of an alpha detector. And I told Derekor mentioned to Derek this possibilitythat even though we might not be able to get useful stable isotope information from speleothems, at least we could determine how old they were, and that certainly interested him.
Now, the crazy thing at that point was that I was thinking about a method which I realized afterwards was totally nuts, and that was to look for the ratio of the two isotopes of uranium, uranium-234 to uranium-238. And I hope that this recording device that were talking into doesnt mind a few technicalities or two, but at any rate I should just say that the half-life of uranium-234 is 250,000 years, approximately249,000 years and change. So, it seemed like a very useful isotope for measuring the ages of processes going on in a cave and, particularly, determining the age of karst formationsof speleothems.
So, with that in mind we thought, well, well build a system for analyzing this. And we got a graduate student to work on this project. He was a student who had come to work with Derek, but he was a chemist by training. He had done an undergraduate degree in chemistry at [the] University of Hull, if I remember correctly. His name is Peter Thompson, and he later went on to found a magazine about caves. It was published in the western U.S. And Derek tells me just the other day at lunchhe tells me that Pete sold his magazine for a million dollars or something like that, and has kind of gone into retirement.
HS: But its possible to do such a thing. So, Pete Thompson and Derek and I then began to try to date stalagmites. Well, we needed a piece of equipment to do this. A uh, a uh (sigh)what do you call it?
BO: Alpha spectrometer?
HS: Nouh. A spectrometer, yes. An energy spectrometer. WhatI canttheone of my problems now is I cant remember the names of things.
BO: Its the
BO: Let me see. The
HS: Multi! Yeah, analyzer. Yeah.
HS: Multi-energy analyzer. What do you call the
BO: Yeah, thatswell, thats thethats the
HS: Yeah. Thats not exactly the name for it, at any rate.
BO: Multichannel analyzer?
HS: Multichannel analyzer! Thats right, a multichannel analyzer. Thank you. Okay. And it happened that a professor in our physics department, who was working in the nuclear research building, had a multichannel analyzer that he didnt need anymore and so he gave it to us. Except he didnt move it. We left it there because it was too big. In those days, a multichannel analyzer was an object that was about five feet tall and three feet across and weighed about three hundred pounds or five hundred pounds or something like that.
BO: Having huge energy sources.
HS: Yeah. It was amazing!
HS: The thingI mean, if you think of it today. And so, Pete started using this. Now, about this timeand you know, my exact chronology of all these things is a little obscure. Like, I came to McMaster in 1962, and I think the events which we are describing are happening around 1968 or something like that, sixty-seven  or sixty-eight . And about this time, a number of very important things were happening. Not at McMaster, but elsewhere in the world.
First of all, a guy named Chris Hendy was located in New Zealand, and was getting his Ph.D. at the University of, uh, Waikato, I thinkin Hamilton, New Zealandwas discovering that the original studies of speleothems and their isotope characteristics were wrong. The stable isotope characteristics were wrong.
He was showing that if you went deep enough inside of a cavesomething he was quite capable of doing, since he was a good amateur caverthat he would find that stalagmites, which were growing deep inside the cave, were growing in oxygen isotope equilibrium. And, in fact, he was able to develophe developed a test for whether a stalagmite was growing in equilibrium, a very clever idea thatthatwell, he showed that since in a situation where the water on a stalagmite surface is not evaporating, its oxygen composition should remain constant all over the surface. And therefore, if you analyze one growth layer, which was formed from that layer of waterif it didnt show any variation in oxygen isotope ratios, that meant that thethat particular layer, at least, was growing isotope equilibrium. And if you measured several layers in the same stalagmite, you concluded that the entire stalagmite was growing in oxygen isotope equilibrium with its drip waters.
Now, going back in my story to the very beginning while I at was at Chicago in 1950, at that moment, unbeknownst to me, Harold Urey and Sam Epstein and others were showing that if you had a calcite that had grown in oxygen isotope equilibrium with water, you could measure the temperature at which it had grown. And that seemed like a good idea. So, now Chris Hendy suggested that we could use this method to determine paleotemperatures inside caves. Of course the problem with a stalagmite is that if you know what its age is you can obtain a record of its oxygen isotope ratio back through time, but its only the record of the calcite part of the story. You need to have a record of the water as well. And, at least at that point, it didnt seem as if there was any water you could analyze.
So, what Chris and his supervisorand again my memory fails me. [Alec Wilson] But, uh, Hendy andoh, I just dont remember the guys name. He was his professor at the University ofI think it may have beenyeah, Waikato. They concluded that what you would be able to learn was some notion about the gradient in temperature between the equator and the place where the
BO: Cave is located.
HS: Cave is located. That would be aboutbecause they argued that the water would evaporating from the equator at a certain condition and then the vapor was moving to the cave and falling out of the sky and entering the cave, et cetera. So, using this method they published the very first series of speleothem temperature recordsor, not temperature records; well say speleothem isotope records with some kind of paleoclimate suggestions attached to them.
So, we realized that this openedwe; that is, Derek and Pete Thompson and I realized that this now opened up a whole new avenue of study, which is to measure the oxygen isotopic composition of the same speleothems that we were dating, and so Pete set to work doing this. And this wasnt a very difficult thing for us to do, because we had a stable isotope system. We had the mass spectrometer and a, uh, vacuum line, in which we could react calcium carbonate with phosphoric acid. In those days, by the way, the, uh, the mass spectrometer that I was using was a, uh
BO: One room installation.
HS: Was a homemade machine that had been built by a former graduate student of Haroldof Harry Thodes, and it had been just sitting sort of idly. And I acquired it because on my wedding day, uh, I wasI had a wedding dinner and I had invited Harry Thode and his wife to come to the wedding ceremony. And at the end of the dinner, he said to me sort of casually, he said, Would you like to have a mass spectrometer? And so, in a sense, he gave me this mass spectrometer as a wedding present.
BO: Ah, good.
HS: So, that was a good way to get a mass spectrometer. (laughs)
HS: Okay, so this mass spectrometer sat still in the nuclear research building. We didnt really want to keep it in our lab because it needed to have too much kind of life support systems from technicians and liquid nitrogen supply and so on. It was a funny old machine that was rather cranky. But eventually we moved it to the, uha new laboratory was built for me in a brand new building that was constructed at about that time, and I now had my mass spectrometer in my own lab, and I think Pete started to use that machine before he finished his doctorate. I cant exactly remember the timing of this, but I think he didany rate, his Ph.D. thesis was published partly as a paper in Science and it focused on the stable isotope record of the speleothemof a stalagmite from West Virginia.
BO: That was seventy , seventy-one  or something like that?
HS: Uh, yeah, seventy-one  or seventy-two . Something, something about that. Yeah, about that.
BO: So you also, uh, made all the dates, already?
HS: Yeah, we already were doing [that]. So, Pete was doing the uranium series datesoh, yeah! By the way, that was another thing which happened. I think I left out a part of this story. This is the problem with trying to do this kind of a
BO: Development of the
HS: Development. I think, causelet me just say that, uh, there was another foreign individual in this story who should be mentioned at this point, and this is this guy we were talking about a moment ago, Cherdyntsev.
BO: Yeah, from Russia.
HS: From Russia. Now, this guyVladimir? I cant remember what his first name was. AnywayNikolai, maybe. Nikolai Cherdyntsev [Viktor Cherdyntsev] had published a book, which had the curious title of Uranium-234 [English translation of Uran-234]. And why would you write a book with the title of Uranium-234? Well, it wasnt really about uranium-234. What it was was a book about the way in which the daughter isotopes of uranium gradually grow into radioactiveor what we call secular equilibrium with their parent isotope. And the important point is that uranium chemicallythe chemical element uranium is separated from its daughter isotopes when waterwhen the uranium is dissolved in water and moves through the Earth. And, as a result, there is a possibility for finding a sample which contains uranium that doesnt have all of its daughter isotopes attached to itlocked in the crystals of a mineral such as calcite. And this process of trapping uranium without its daughter isotopes in the crystal is beginning a clockis setting a clock to zero. And the hands on the clock basically, or the movement of the clock, is recorded in the growth of the daughter isotopes back into equilibrium with the uranium.
Now this idea really hadnt been at all fully developed by any other scientist to my knowledge until then. There were some other people who had worked on radium disequilibrium and on radon disequilibrium, but looking at the isotopes of uranium and of its daughter thorium-230 really hadnt been really worked out until Cherdyntsev. So, he showed that you could determine the age of a calcium carbonate deposit.
BO: Looking at this
HS: By looking at the ratio of the thorium-230 daughter to its parent uranium-234, and also, the ratio of the uranium-234 to its parent uranium-238, et cetera. So, these two simultaneous decay processes gave you a clock with which you could determine the age of some kind of calcium [deposit]. But he hadnt really applied the method very extensively. So, realizing that this was another way of telling time which was much better than the 234U/238U ratio of measurement, which I had originally in mind, Pete Thompson set to work doing these measurements. And the 1971, or seventy-two , paper on the Virginia cavesand, furthermore, his thesiscontained the first uranium series dates on speleothems, uh, that actually were really pointing towards some useful kind of paleoclimate information.
BO: Information, yeah. (speaking at the same time)
HS: Okay. So that was the beginning of everything.
BO: But, you know, I was at the very early time when I start[ed] doing alpha counting.
BO: Because even in ninety , when I went to Stein-Erik Lauritzen in Norway.
BO: And he was at your lab for a while.
HS: Yes. He was still doing alpha counting.
BO: Yeah, he was still doing alpha counting. So I had this column preparation, column separation.
HS: Yes. Yes.
BO: Purification. How was this stuff at the very beginning? Because
HS: Okay; well, Ill tell you theres another story thatas usual, Im leaving out little bits of this story. In theduring the Second World War, the U.S. developed the technology for making nuclear weapons. Now, in order to do that, it had to perfect a huge amount of radiochemistry of the nucof the, uh, transuranium elements and of the elements ofin the family of uranium. And all of the information coming from that project, from those projects and the related information, was eventually published in technical manuals which you could buy from the U.S. government, which described in great detail how you could use ion exchange resins to separate uranium and thorium from other elements. And at the same time, there was a marvelous chemist inI think he was Viennaby the name of [Johann] Korkisch, and he had picked up on this thing and he was expanding on it and developing even more elaborate methods. So, between the work of Korkisch and of the various researchers from the
BO: Army. Okay.
HS: from the Manhattan Project, you now had some techniques for separating uranium and thorium isotopes and even protactinium, which was an element we didnt really pay that much attention to, from the other constituents in a rock; and, therefore, be able to concentrate them and put them in front of the uraniumof an alpha detector and measure the uraniumthe alpha spectrum with a multichannel analyzer.
HS: So, it was really thanks to the, uh, atomic bomb project that we were able to do this, because if we had had to develop this, or, you know
BO: It would have taken some more years.
HS: It would take many years, and frankly, I would never have done it because I was not about to become a radiochemist, which was for thenow, fortunately for us also, Pete Thompson has his background in chemistry, and if Id had a biologist or a, you know, whatever, or a geologist, even, for a graduate student, it would never have taken place either. But because Pete [was] smart enough to realize what steps in these procedures were important and what you can change and modify and fool around with, he got the process going to the point where we were able to actually do this.
No. (laughs) You know, the funny thing about this is that back in those days, although we knew pretty much how to do this, we were pathetically inefficient at doing it. And by that I mean thattheres a quantity called yield, and yield means what fraction of the total number of atoms of what youre looking for that were in the sample eventually end up on theon your detector or in front of your detector. And we would typically get yields which are on the order of 5 percent, 10 percent, 15 percent. And with yields like that, it was very difficult to count enough activity to be able to do this. And even to the very end of the days in which we were doing alpha spectrometry, I would say we were very happy if we got an analysis which gave us a yield of 50 percent, and I dont even now know why it is that our yields were so poor.
But in spite of these terrible drawbacks in the chemistry and the fact that the technique was working in such a ridiculously inefficient way, we still were able to get precisions on the order of 5 to 10 percent in the uraniumin the uranium series dates, in the alpha dates, and that was pretty good for telling the age of stalagmites back to, lets say the last interglacial. Now, let me justcan I
HS: If I could just go on talking about some of the background of this thing. At about this same time another group, interestingly, totally unbeknownst to meand I eventually got to know these guys very wellwas developing, uh, U-series [uranium series] dating of speleothems. Actually, there were two groups.
There was a laboratory inat the University of Pisa under the direction ofwell, the person who actually did the dates was a woman named [Giuseppina] Fornaca-Rinaldi. I forget her first name, but that wasshe had a hyphenated name, Fornaca-Rinaldi. And she and her supervisor who, I think, was named [Ezio] Tongiorgiyeah, Im pretty sure it was Tongiorgi. They extracted uranium and thorium from speleothems and they claimed to be able to determine their age; and they actually applied the method, interestingly, to speleothems from some archeological caves. Now, Im mentioning this now because
BO: We will go to the
HS: Thiswe are going to get to that a little later on.
BO: Yeah. (speaking at the same time)
HS: But Ill just say that this is one of the ironies of my life, that I always find myself at the right place at the wrong time. In 1968 and sixty-nine  while Pete Thompson was laboring back at McMaster to finish his doctorate, I took my first sabbatical leave, and where did I take my sabbatical? I take ittook it in the Istituto di Geologia Nucleare at Universit di Pisa, Via Santa Maria 22, in a building which was built probably in the fourteenth century and had walls which were about two meters thick. So, its rather difficult if you ever wanted to run a pipe from one room to another in this building, because you have to drill a long way.
Any rate, so, in this laboratory I was working not on stable isotopes and speleothems, strangely, because I hadback home I had a student who was working on it. But I was working on oxygen isotopes in sulfates. Now, I must admit that in my whole research career, my contributthe various things that Ive made contributions to, I would say probably the least important study I ever did was the oxygen isotope studies of sulfates.
Uh, but I had a good time in Pisa because its in Florin, uh
BO: Its not far from
HS: Not far from Florence.
BO: Florence. (speaking at the same time)
HS: And its in
BO: Close to the sea.
HS: And its in Tuscany, and we ate very good food and my wife studied how to play the cello, and generally I had a very good time, and I was on a Fulbright Fellowship, too. And Im sure the Fulbright people got their moneys worth from what happened afterwards. But in the course of this, I got to know Fornaca-Rinaldi and saw what she was doing, but I was not really that interested in what she was doing at that point because this was just before we made our own
BO: Karst contribution.
HS: Karst contribution to this thing, and I realized only afterwards that she was doing itdoing the right thing by doing it the wrong way, and that the results that she was getting were probably ratherrather screwed up, shall we say.
Uh, listen, if we could take a break, I need a glass of water.
HS: Is it possible, possible to get a drink of water somewhere? [If] Ive got to keep talking like this, you have toah! There we go. Perfect.
BO: Brand new.
HS: A brand new bottle. This [is] a very important piece of equipment for this interview. Zehpher-rillis? Zephyrhills, okay.
BO: Thats just across the campus, on the other side, a couple of miles from here.
HS: Okay, there we go. All right, so, umso, Ive just mentioned this in passing, because there I was in the same building with Fornaca-Rinaldi and I wasnt really paying that much attention to her. But a little while later, obviously, we became interested in this and were doing exactly the same things that they had been doing.
And then the second laboratory [person] that I want to mention, which is much more relevant to what were talking about here, was that Jean-Claude Duplessy, who is in thewell, at that time was in [the] University of Paris, I believe. Im not exactly sure, but somewhere in France, anyway. And he had picked up on the work that Chris Hendy was doing, and so he found a cave in France, which had a stalagat least one stalagmite and he did an isotope profile in it, and
BO: The quarry was Clamouse [La Grotte de Clamouse], if I remember well. The paper
HS: Was it Clamouse!?
BO: It might be.
HS: Oh. Well, maybe; it could be, couldvery likely, because it was certainly a cave you could get aeasily get a stalagmite from.
BO: Easy access and lots of speleothems in.
HS: Yeah, okay. So, there he did this paper and he showed that there was a kind of isotope signal in the thing. So, uh, this was at about the same time that we were doing our work. Now, the interesting question was what the isotopes signal was telling you?
Um, you know, theres a curious thing about all the work that has been done on speleothems in those years and every subsequent year to the present, which is that people have very widely made use of plotsgraphs of the relationship between the 18O/16O ratio, the 18O value of a stalagmite, and time, and said that this is a record of paleoclimate. The problem is that with some graphs the high point of the 18O represents a warm period and the low point represents a cold period.
BO: (inaudible) Cold period.
HS: And on other graphs its the reverse. So, it appears that this is a very ambiguous signal. It tells you something about climate, but you have to know how to interpret it at each particular location, and in particular at, uhif you have a very short record which happens to include, lets say, a glacial and an interglacial transition, uhand in those days we didnt even know what the date of what we now call [Marine Isotope] Stage 5e is. So, you might have some argument as to whether the top of your peak represents the warm period
BO: The warm period. (speaking at the same time)
HS: and the bottom of it represents the cold period or the other way around. And, in fact, Duplessy and Emiliani got into a bit of fight over which was which, because Emiliani was having an argument as to what the date of the lastthe warmest part of the last interglacial was, and in those days he believed that it was 100,000 years and not, as we know it today, as 130,000 years. And soand thatits kind of getting off
BO: Its history.
HS: Its an interesting bit of history, but we were kind of just sort of innocent bystanders of this story. But at the same time we were realizing from this the kind of problems that you would get into as you got further into the study of these isotope variations of oxygen in the calcite component, all right.
So, in this same period, and actually, still while Pete Thompson wasI was surprised; the other day I was looking at Pete Thompsons Ph.D. thesis, and I had forgotten that he was still completing his thesis when we began to do fluid inclusion work. And in fact, he included some early fluid inclusion studies in his thesis.
So, what about this fluid inclusion story? We are talking now about the problem of determining paleotemperature using the concept that Chris Hendy had invoked of applying the calcite water fractionation to a speleothem. Sometime around 1970maybe seventy-three  or seventy-four , I cant exactly say whenI guess I was looking at a book onfluid inclusions, water fluid inclusions. Geologists, for a very long time going back into the nineteenth century, had known that some rocks contain small, uh
HS: Bubbles. Pockets, little enclosures ofwhich are filled with water and, if the rock is in a rock form that a high temperature as in deep in the earths crust, the water might be very salty; it might contain a lot of crystals in it as well as the water. But, uh, apparently it hadnt occurred to me or anybodywhy should they think of it?that there might also be fluid inclusions. We call these things, by the way, fluid inclusions. There might be fluid inclusions in stalagmites, and in fact in speleothems in generalflowstones (inaudible)and even stalactites. Well, that might be an interesting thing to look at because the fluid inclusion is believed, generally, to be a sample of the water which was present at the surface of a crystal at the time the growth surface was just passing the point where that fluid inclusion was forming. And so, therefore, it would be a trapped sample of the water
BO: From that time.
HS: from that time. And if you have a stalagmite which grew over 50,000 years, the fluid inclusions could, in principle, give you a sample of the history of the water through that period of time. Now, what can you learn about that water? Well, theres not much dissolved in the water. Its not a question of determining the change in the salinity of the water or trace elements, but certainly the important thing for us was the isotopes in the water.
Hydrogen and oxygen make up the water. So, we could learn something about the hydrogen isotope ratio and the oxygen isotope ratio if we could extract the water, or so it seemed. The first trick we had to do was to develop a way of extracting the inclusion from the speleothems. By looking at the speleothemat some samples of stalagmite under a microscope, I concluded that they must contain about a tenth of a percent of fluid inclusions by weight. I was just guessing on the basis of the areaof what fraction of the area of a thin section of stalagmite was hollow, was
BO: (inaudible) Emitting!
HS: An inclusion. And so, I figured we needed to crush about one gram of stalagmite to have enough water to analyze. Ah! (sighing). So
BO: This was already in seventy ?
HS: Well, Im not sure whether I started to do thisI knowwell, okay; the point is that by 1976 we published the first paper on fluid inclusions andhow were we measuring the hydrogen isotope ratios? See, this is what I cant remember. Ah, this is a good question. (laughs)
BO: Cause Im puzzled because recentnowadays you are also trying to develop a better method to do extraction of the fluid inclusions.
HS: Yeah. Yes, right, right. (speaking at the same time) Okay, yeah, butokay, what Im trying to figure out now is, where did I do the hydrogen isotope measurements of this? Because at that point I dont think we had a hydrogen isotope mass spectrometer. We must have had, though. Oh, thats weird. You knowhmm. Ill have to go back and think about that.
At any rate, at that point we first developed a kind of weird crushing device which consisted of a kind of a bellows, a copper or flexible metal bellows, and a screw, which allowed us to screw down this bellows and crush the stalagmite, the piece of stalagmite, until some of the inclusions trim out.
BO: Are released. (speaking at the same time)
HS: Were liberated. And then that didnt work so well, and particularly, the thing began to leak very quickly. So, this was the stage of Pete Thompsons thesis. And then, later on, when Russell Harmon came to do a Ph.D. with me, we moved on to a more elaborate method, which actually worked pretty well and which we stayed with for some time, and that was to take a length of stainless steel tubing and to put a piece of stalagmite in the middle of the tube with some glass wool on either side so it couldnt move around, and then we evacuated this tube with some kind of flanges, which he put on either end. And then we put this under a hydraulic press right at the spot where the stalagmite was located and the hydraulic press crushed the stalagmite and then liberated the water, which was trapped in the fluid inclusion, and then we were able to analyze the D. Andokay, sothis is really baffling me now because I cantI should be able to remember this. Any rate
BO: You are right; there are so many things happening.
HS: Yeah, happening in my lifetime that I cant even remember what I was doing.
But in any case, uh, we showed, first of allwell, what I should say is that it was pretty obvious from thinking about the question that we shouldnt be looking at the oxygen isotopic composition of the water, because the water itself had been trapped inside of, you might say, a bottle which was made of calcite for 50,000 or 100,000 years and had probably had continued to exchange its oxygen isotopes with the bottle so that it no longer remembered the original oxygen isotopic composition. But there was no hydrogen in the bottle. So, therefore, the hydrogen isotope ratio, the ratio of deuterium to hydrogen in the water, would still be preserved and remembered from the time when the stalagmite had grown.
Now, it turns out that theres a very good relationship between the hydrogen isotope ratio and the oxygen isotope ratio in drip waters in caves. We showed that ourselves measuring drip waters from caves, and its also known insince the drip water is basically a sample of meteoric water, its much better known in meteoric waters from the work of
BO: Craig and
HS: Craig, and of [Will] Dansgaard before that. That
BO: Meteoric water line.
HS: There was this so-called meteoric water line, which relates to D and the 18O of the water. So, we could, therefore, use the D value to infer what the 18O of the water must have been, and we had to assume that the meteoric water line had remained constant through time. And we did this. We measured the paleotemperatures of speleothems by this means, and the first paper on this was published in Geochimica in 1976, and I was the senior author and Derek and Pete Thompson and Russ Harmon were the co-authors on this paper because they had all contributed to the analysis and, of course, the samples and the dating. And then we tried to move on with this method, but things got a lot more complicated very quickly.
First of all, I had a marvelous graduate student, or Derek and I had a marvelous graduate student, named Chas Yonge, Charles Yonge. Now, Charles
BO: Young or Young-gee?
BO: Okay. Because he was in Romania [at] one of the meetings I organized.
BO: And everyone was calling him Young-gee.
HS: Young-gee. Well, no, his name was really Yonge.
BO: Maybe. But he spent some time in Indonesia and
HS: But he was a very quiet guy, and if you called him Young-gee he wouldnt bother to correct you.
BO: Okay. (laughs)
HS: Very quiet guy. Very nice person, and he was a physicist by training. So, he set to work to build a deuterium-hydrogen mass spectrometer for our lab, and not only that but to do a lot of work on figuring out exactly what was going on with fluid inclusions in speleothems. Now, in fact, a lot of the work that he did ended up being more of the drip water aspects ofbecause with the hydrogen isotope measurements, we can now further confirm that we had donewe were doing the right thing by assuming the meteoric water line for the drip waters because, in fact, the drip waters we could show were on the meteoric water line.
But then Chas did a whole bunch of experiments [in] which he heated the stalagmites and showed enormous excursions in the deuterium-hydrogen ratio as the water came out of this stalagmite while it was being heated, and this scared the hell out of us because we didnt know if these were real variations inlike if there were multiple populations of fluid inclusions which were giving different isotope ratios and which came out at various times or what was going on. And it wasnt really only until, I would say, probably last yeara very nice study, which was done, that really has led to some understanding of what goes on when this heating is taking place.
But, at any rate, Chas and I worked together on this for a few years, but unfortunately, not very much of what he did was published. In fact, people still refer to his Ph.D. thesis.
BO: Yeah, [it was] at least one more paper that I, well, actually recently used.
BO: Because its one of the first that compares the precipitation a little bitand you got a lot of samples from throughout North America and Canada in that paper.
HS: Yeah, yeah. (speaking at same time) Yeah, and then we publishedthere was an International Atomic Energy Agency symposium on the history ofisotopic history of water or something like that. I think it was organized by Peter Fritz, at that time, who was at Waterloo [University]. And Chas and I gave a paper at this symposium in which we presented some of these fluid inclusion data, and I guess that was about the major publication on this thing. And then there was one more paper that Russ Harmon andoh no, theres another marvelous person I shouldwhose name I should mention here, which is Jim ONeil.
Jim ONeil is, of course, very well known in the isotopestable isotope community for having done a lot of calibration of isotope fractionations in silicate systems. But he was also a student at [the University of] Chicago when I was doing my postdoc and so weve been old friends. And he wasat the moment that Russ Harmon and I were working on this stuff, Jim was a postdoc at Caltech. And so, I went to Caltechoh! Yes, I think thats right. Yes, I went to Caltech, and Pete Thompson was also at Caltech at that time, by the way. Thats another story. He had finished his doctorate and he went there as a postdoc to work with Sam Epstein on something totally different; he left speleothems altogether and went to work on cellulose, on hydrogen isotopes and oxygen isotopes in cellulose.
At any rate, so I went to Caltech and we did the analyses and published a paper, which kind of firmed-up our understanding of the isotopic composition of fluid inclusions, at least the hydrogen isotopic composition of fluid inclusions. And out of that we, I guess, concluded that it was in theory at least possible to do significant paleotemperature measurements. The problem was that until Chas Yonge came along, we didnt really have a stable hydrogen mass spectrometer to do this on, and after Chas, left the machine really wasnt working very well. He seemed to be the only person who was able to make it work
BO: Knew how to run it. (speaking at the same time)
HS: because it was a homemade machine. Again, one of these machines that had been put together from bits and pieces that had been sitting around. And so, I kind of stopped doing stable isotopes with speleothems, or lets say fluid inclusions, and went on to doing other things. All right, so thats, you might say, the end of chapter two, which is the end of my early work in fluid inclusions; and well come back to fluid inclusions a little latter on.
BO: More, yeah, more recent.
BO: Let me ask you something about Chas, because Im not sure if he was still with you or he was somewhere else when heor if you are behind this stuff, actuallywhen he had done the stable isotopes in ice.
HS: No. That was definitely not me at all.
HS: No. I didntin fact, I wasnt even aware that hed done such stuff.
BO: Yeah, he [did] have someone of the glacierscave, uhice deposits in one of the caves in Canada.
HS: Ah, right. No, thats totallyI think he went off on his own at this point because
BO: He had some oxygen and hydrogen measurements.
HS: Because he went off to Alberta to work in the laboratory of John Gray, who is a professorwas a professor at that time in physics, and he workedhelped John to do analyses of stable isotopes in various types of materials and thats probably when he did this work.
BO: I see. I see. So, basically
BO: Basically, McMaster was [at] the forefront of dating, beginning of dating, regular datings on speleothems.
HS: Yes. (speaking at same time)
BO: I mean, Fornacathey tried something in Pisa. TheyI think Duplessy[there] was only the one paper that he had.
HS: That was the only paper he did on that.
BO: Yeah. So
HS: After that he dropped it completely.
BO: Yeah, I would not say that was a real laboratory working on speleothems.
BO: So, basically McMaster is the pioneer.
HS: I guess we were, right.
HS: And we kept doing it and kept doing it, because after that we had Mel Gascoyne, who came and did his Ph.D. on more speleothems.
BO: Geochemistry and some other things.
HS: Yeah, but he was really working on dating of speleothems.
HS: And he developed the protactinium method, which we didnt really take too seriously, but he showed how you could use this other isotope protactinium, which was the daughter of the rarer isotope of uranium, U-235.
BO: Thats very used in coral dating.
HS: Yeah. It has been used; its never really caught on in a really significant way because theres all kinds of problems with, uh
BO: And Larry [Lawrence] Edwards, in his lab, was doing quite well.
HS: Yeah, yeah, right, yeah. (speaking at the same time) I mean, now that you can do it by mass spectrometery, I guess that it sort of picked up a little bit, butat any rate, so, he did a bit of protactinium work. And then the other person who I have to mention, just while Im kind of reviewing the people who worked with me, was Alf Latham, who did this amazing study of paleomagnetism on speleothems.
HS: Yeah, working in Mexico and various places, and showed that you could reconstruct Holocene paleomagnetic variations very nicely with speleothem samples even though we didnt really know, and probably even to this day we dont know, what the, uh, (sighing) magnetic carrier is in the speleothem. We assumed its very finely divided magnetite particles, but
BO: Or hematite.
HS: Or hematite, but we could never really do the convincing study, which would be to do alike a heating experiment to tell what happens, because when you heat stalagmites other things happen to the stalagmite before the signal begins to change. (laughs) Like, it becomes decarbonated. All right. Anyway, so
BO: I just have one point to finish with your chapter now, because this is actually your history, and then I just wanted to tie it to something else. When I moved back from Norway, doing part of my Ph.D., and go back to Cluj, I was talking to Derek. I said, Hey, Derek, you have an alpha spec. I know you moved on [to] TIMS [thermal ionization mass spectrometry]. What are you doing with that?
HS: Oh! I remember this.
BO: He said, You want it!?
HS: I remember this so well.
BO: And he said, Yeah, I have it.
HS: And so Derek said to me, You know, we have these alpha spectrometers. Why dont we give them to our friends in Romania? and I said, Marvelous idea! Pack them up and send them off!
BO: Yeah, and unfortunately, they came to Budapest and they [had been] shaken on and off and something like that.
HS: Oh, no.
BO: So, we got it into Cluj, finally.
HS: Yeah, right.
BO: We thoughtit was a kind of smuggling over the border because if I would tell anyone what it isand, actually, I told one.
HS: Oh, God. (speaking at same time) Oh, right.
BO: You know, the small chambers for measuring that
HS: Yes, yes, right.
BO: And somebody asked me and I said, Well, Im [being] frank, I cant tell you what is it, and he said, Okay, in my list, it doesnt appear to have this kind of [harmful] device. So, if I will send [to] Bucharest a mention that you are want[ing] to cross, they will say, Okay, we dont have it in the list you have so [you will have] to wait months. So, [I am] pretending I have seen nothing. So, we move everything to the university, put it down into the basement [and] manage to find the source because all the chambers came without [a counting] source.
HS: Yeah, thats right.
BO: And the only problem we run into was the multi-chamber analyzer because of this shaking off and on.
HS: Shaking. [It] wasnt working.
BO: It was lighting up, but the big screen to show you the spectra was not.
HS: Oh! Right. Oh, God. (laughs)
BO: So we had to find the physicist to look in it, and we managed to put it [to] work for a couple of weeks and then something [would] break down finally.
HS: All right, well
BO: Thats the end of the alpha spec.
HS: So, you never got dates from it?
BO: We managed to get, like, three dates or something.
HS: All right.
BO: And then its gone.
BO: Yeah. Well, well move on to ICP [Inductively Coupled Plasma] [spectroscopy] now. (laughs)
HS: Okay. You and everybody else moved on. All right, so let me move on to, should I say, chapter three. (clears throat) This is Henry the archaeologist.
Around 1974 or seventy-five , lets say, my wife, who was watching me do all these strange things, said to me one day, very casually, she said, Rocks are boring, and I said, You know, youre right. They are rather boring for most people, but for me they very interesting. [And] she says, Yes, but why cant you work on something which would be more interesting to me? And since I was a very agreeable husband, I said, Well, Ill look for something to see if there was anything I could work on.
And just about that timeI cant actually remember the exact circumstances, but there was a cave in New Mexicoand you know, again, its going to be difficult for me to reconstruct the exact sequence of events. But this was a cave called Sandia Cave. And from the name you would guess that its probably located in the Sandia
HS: Mountains, which are just next to Albuquerque. Indeed it is. And there some time in the 1930s, I think, a Boy Scout who was climbing around there discovered some Indian remains in the Sandia Cave. And so archaeologists began to dig in the cave, and by the 1960s or so, they had uncovered a long sequence of deposits. But the interesting thing was the deposits were capped by a stalagmiteactually, by a flowstone, I should say. Not aby a flowstone. And so, I had been talking to someoneI dont even remember how, who or whereand this subject came up and I said, You know, maybe it would be possible to date this thing.
So, very soon afterwards, I think it was Vance Haynes, who was a very noted archaeologist in those days in Arizona, managed to get a sample of the stalagmitic layer from Sandia Cave and send it to me. And I dated it and we put it through our mass spectrometerthrough our alpha spectrometer system, and it turned out to have an age, pretty clearly, of 250,000 years. Ta-da! What? We have humans forming deposits, which were covered by a stalagmite 250,000 years ago, [an] epoch making discovery.
Well, of course, it didnt turn out to be that way. What were looking at here, in fact, was a crevice in the cave where the flowstone had been sitting on top of some softer material; the softer material had been eroded away and then the Indians whoI mean, not the Indiansthe people who had been living in the cave had created deposits.
BO: Shelter. (speaking at the same time)
HS: Under the shelter. [They] had inserted themselves under this level, and that was pretty obvious to me. But there was at least one crazy archaeologist who unfortunately heard about this discovery that I made, so-called discovery, and began to claim that this was a natural age, and so I had to fight pretty hard to make sure that this was never published as a statement that the age of this deposit was 250,000 years. But it turned out [that] a light in my head [went on] somehow. [This was] the idea that one could use uranium series as a method of dating archaeological stalagmites.
So, I first went off to the libraries to start to look for other examples of caves where there were stalagmites associated withor flowstones or whateverassociated with speleothems, associated with archaeological sites, and indeed there were a lot. And it sort of came back to me at this point. I remembered good old Fornaca-Rinaldi, who had been dating a cave. I think it was Arene Candide, in fact, which is in Italy, which is one of the caves which has been dated more recently by uranium series. And I thought, well, this is interesting, because it opens the possibility of doing research in Europe and the Old World, which is something I kind of had in the back of my mind since my familys roots go back to Hungary and family in Israel, and there were some caves in Israel.
So, I thought about this thing, and I began to do some analyses first in a very preliminary way using samples that other people had given me. In particular, there was a professor at the University of Paris, a very famous man named Henry de Lumley, whohas youI dont know if youve heard of him.
BO: I [have] heard of him.
HS: Youve heard of him. And when I told him what I was doing, he very happily sent me a whole bunch of bits of stalagmite, but he never told me exactly where they were from. And I found out that this was sort of a typical thing that de Lumley would do, is that he would find out whether you were doing anything useful and then he would get his own
HS: Then he would do it himself.
HS: Get his people to work on it himself, I suppose. So, it was the year 1975 and I had another sabbatical coming up, my second sabbatical. So, I set up my sabbatical as follows: that I was going to go(laughs) what a complicated story this is. I was going to go to three countries. First of all, in those days McMaster University had a relationship with the government of Hungary through a thing called the Institute for Cultural Exchange. Okay, it [was] Ka Ka KaI cant remember what the wordsKapcsolatauh, anywayKulturalis, uh, anyway
HS: Something, something. [At] any rate, and these people had money, and so they could pay for me to come to Hungary and spend a month at their expense studying the caves of Hungary and collecting samples of stalagmite, which I would then take back to Canada and date. And my wife and I and my son, who was in those days about five years old, flew to Hungary. We were very happy to be in my oldmy parents old home country, and I even had some relatives who were still living there at that time. And we lived in an apartment in Buda, and then I visited archaeological sites.
Now, what were these sites that we looked at? Theres one very important site, which goes by the name of Vrtesszlls, andI dont know if you know abouthave you heard about this site?
BO: Yeah, of course. I know all your papers there.
HS: Okay, you know my papers. But Vrtesszlls was the type locality of a very curious lithic industryoh, and by the way, at this time I was also having to teach myself archaeology, and particularly Paleolithic archaeology, because this is not exactly a part of my education at Caltech or University of Chicago or anywhere. So, I was going to the library and reading all these books. So, at Vrtesszlls there was an industry which made tools at of tiny little bits of flint, and they figured that it must be very, very old. And there was a particular Hungarian geomorphologistoh, boy, am I going to remember his name? Uh, I should remember his
HS: E, it starts with an E. Uh, anyway, I cant remember his name. [Pecsi Marton] At any ratewho argued on the basis of the number of terraces of a particular
BO: Its on the Danube?
HS: Its not the Danubeits a tributary of the Danube. But there was a particular little stream there which had these stream terraces, and by counting up from the terracefrom the bottom and arguing that each one of these represented an interglacial that you could count up, and youd say that the site must be 450,000 years old, or whatever. And so that was one site which we measured, and then the other site was a place called Tata. And Tata was also a prehistoric site from the Paleolithic, which was a flowstonenot actually a flowstone; it was a spring deposit. So, I have to admit that
HS: Tufa. So, I have to admit that were getting away, a little bit away from karst here, becauseunless you want to include karstic areas which have tufas in them. At any rate, it was a very important part of my history. So, we did dates on these two sites, and then that was my firstthe first month of my sabbatical, and then we packed up our things and we drove in our little Fiat, which we had bought when we arrived in Europe.
We drove down to Greece and to a marvelous cave called Petralona, and there I met a guy named, umoh God, here goes the memory; the memorys going crazy again. Uh, Aris Poulianos, Aristoteles Poulianos. Now, in the cave ofthe cave of Petralona is a very fine
BO: Its a very famous one, yeah.
HS: A very famous cave. Its in the Khalkidiki Peninsula, which is these three fingers that pointthat stick out of the northeastern part of Greece, and I guess theyre pretty well all karstic landscape. And in the westernmost of these fingers is this cave of Petralona, and sometime in the 1960s a skull was found in this cave of a very primitive hominid. When it was first discovered, it was covered with layers of calcite, but the calcite was finally removed, and then they revealed early species of the genus Homo with very large brow ridges and a relatively small brainanyway, something on the order of Homo erectus.
So, the date of this thing was not known, but Aris Poulianos had, I guess, had heard something of what we were doing. I dont remember how the connection was made, but he invited me to come down and go into this cave. Well, when I got to the cave, I realized that this was a disaster zone because thealthough the cave was full of
HS: Speleothems. Many, many interestingit was a highly decorated cave, but the place where the skull was supposedlyhad been recovered was a little niche hidden behind a kind of a wall of flowstone, which was filled with sediment, and the skull, of course, wasnt in this site anymore. It had been removed, and there was some argument as to exactly where in these layers of sediment the skull had been sitting. But Poulianos thought he could point to the spot, and he said, We have to date the flowstone, which is in this horizon.
Well, later on I found out that Poulianos didnt have the slightest idea where the skull had been found, because it was found by a shepherd who had lost some sheep and had gone into the cave looking for them. And (laughs) it was only many months later that Poulianos had been into the cave, and there was that argument that went on for some time as to [the] exact location of the stalagof the skull.
HS: And then in addition, there were another series of layers that had flowstone horizons and that he felt were correlated with that location, which he had me date. And these things alsothe relationship of them to the exact time of hominid occupation was not exactly clear. Even more frustrating was that there were no artifacts in the cave. So, it may be that the cavethat the skull was dragged in there by a carnivore.
HS: A hyena or some other animal, and that it didnt really belong in the sense of an archaeological
BO: Population living there or something else.
HS: There was no population; it was deep inside the dark zone of the cave.
BO: Oh, okay.
HS: And so I began to understand with my studies that people only lived in the mouths of caves, which is bad news from some points of view but good from others.
The third leg on my three part sabbatical was in Israel. We spent the longest timeI was a visiting professor at Hebrew University of Jerusalem working with a guy named Yehoshua Kolodny, or Yeshu, as we all called him. [Its] funny, you know, Yeshu nowadaysmost people, when you say somebodys name is Yeshu they say, Oh, you mean Jesus, because theres these crazy people who are Jews for Jesus who think thatbut they call Jesus by the name of Yeshu. But Yeshu was just
HS: Yehoshua, and he was my buddy. He is my buddy.
At any rate, so he had a student named Paul Aharon, who was just finishing his doctorate, and he hadand Paul had built an alpha spectrometer setup for doing uranium series measurements on stuff that was found some evaporated pools in southern Israel. But at any rate, the equipment was there, so I took it over and I began to sample stalagmites inflowstone in stalagmites in caves in Israel in archaeological locations. And the person I was most indebted to for this phase of my work was Paul Goldberg, who is a guy who works on cave sediments and still does work on this subject; hes a professor now at Boston University. So, Paul took me around to virtually every important cave site that was known in Israel, and wherever we could we collected samples.
BO: There were no problems with collecting at that time?
HS: Absolutely none! Well, first of all, the archaeologists were delighted that there was somebody that was going to help them know what the age of these sites were. And second of all, the Department of Antiquities and these kinds of people were much more relaxed in those days. They had other things to worry about, so we could just go in and hack away at these things to our hearts content.
So, the sites that we worked at werewell, I guess the one where we got the most interesting results was a site called Zuttiyeh, which is in the Valley of thewell, its some place near the Sea of Galilee; and we got some dates there which showed that a particular horizon where they had particular interest in archaeological assemblage. Now, these were artifacts; these are stone artifacts imbedded in theactually imbedded in the travertine that theyI cant remember the exact ages, but I think they came out around 180,000, which was kind of neat because nothing was known of the age of these things before then. And there were various other sites that we looked at.
The most important cave site in Israel, unfortunately, turns out to be very poor for this kind of work. This is a site called Tabun, and I have actually done a lot of work in Tabun, subsequently. I dont know how much I should talk about that because itswell, its a cave site.
BO: Its a cave site, and itswell, most of the things in Israel has something to do with the migration of humans from
HS: Oh, yeah. Very, very much, very much. Okay, okay.
BO: And its really, really, really well connected to the
HS: Yeah, okay. Listen, by now its now a quarter after three, and I dont know, Im not moving very fast. Maybe I should move through time a little bit faster and
BO: Why, as you please. I mean, we have it recorded and then
BO: Well see what we do. I mean, this is history.
HS: Okay, all right. (speaking at the same time) Well, I might skip over some of the details here, becauseI mean, youre making me remember things which I had almost completely forgotten, and Im glad youre making me bring these things back to my mind.
Okay, so I spent this year in Israel and the result of it was I published at least a couple of papers on U-series dating of archaeological sites in Israel, which sort of started that process. And it became apparent at about this point that the uranium series dating had its limitations, because the number of sites where you got stalagmites in critical association with
HS: culture was relatively limited. The other important area that I should mention that I worked onwe went back to Europe in subsequent years to France and worked in an area of the southern central part of France called the Charente district and worked in a cave called Lachaise and did some uranium series dating there. Lachaise is a cave which has at least five different levels, which have remains of Neanderthals in it. So, that was quite an interesting cave from that standpoint, and we got dates from pretty much every level that had Neanderthals associated with it. We were able to show a history ranging from about 250,000 to about 100,000.
And at this point, by the way, I should introduce another person into this record who worked with me on Lachaise and did her masters degree, but not her Ph.D., on this. It was a woman named Bonnie Blackwell. I dont know if you knowdo you know this name?
BO: Well, I knowyes.
HS: Yeah, you know who
BO: I just want to know where you go with it.
HS: Okay, because Bonnie was a very energetic, young woman. Shes still an energetic woman and I think of her still as very young, and she just wanted to do everything and, unfortunately, sometimes she wanted to do more than probably was good for her. So, uh, eventually she went off and did a Ph.D. on something which was totally stupid. I wont even mention what it is. But she ended up coming back to work with me in 19the late 1980s, I guess. I think some time in the eighties [1980s]. Yeah, eighty-three  or eighty-four , something like that. [She was with me] as a postdoc working on electron spin resonance dating. That was even before Rainer Grn came to work with me. That was the early days of my ESR [electron spin resonance] dating.
BO: So, how did you got involved in this one?
HS: In ESR?
HS: Okay, thats another story. Ill get to that. Lets leave that for a moment. I just want to go back to say where else U-series dating of archaeological sites took me, because this kind of a method, you know, once youve realized you had this tool in your hand, you want to start looking all over the world and telling everybody youve got this thing.
Unfortunately, the one part of the world you cant really use it very well is in North America, because the archaeological history of America doesnt go back far enough; lets say the Americas, period. So, you really have to be working in what we always refer to as the Old World. And so, in no particular order, Ill just mention that we worked in northern Spain in caves on the northern coast of Spain near the town of Santander, where I worked with Les Freeman and various other people in their whole series of caves. Of course, the best known of them is Altamira, but we didnt go into Altamira because, you knownot very happy about that, but we got samples from other caves there. And the main one, which we got dates from, is a cave called, uh (laughs)anyway, leave that. Ill say it if it comes back to me; Ill remember what it is.
BO: No problem.
HS: [It was] a very interesting cave, which hadoh, El Castillo! That was the name of the cave, El Castillo. All right, and thenI mentioned that I worked in the northern part of France, and then we also went down toI went down to the southern part of France to a famous cave called Arago, which was excavated by that same Henry de Lumley, where they had found some of the most primitive hominid remains known at that time. And they had a series of flowstones in this cave, which we tried to date.
And Ill just throw out another part of this story at this point, which is kind of relevant. This is the notion of the dirty calcite problem.
BO: Yeah, I was thinking to ask you when you start doing in Hungary the tufa.
BO: Because most of the tufa sometimes act as a open system.
HS: Okay, correct.
BO: You will need an isochron for that.
HS: Okay, all right. So, what happened was, uh, there is an interesting problem in uranium series dating, which is that what youre measuringuranium series dating, what is this, anyway?
Were measuring the ratio of a daughter of uranium-238 and the thorium-230, and were measuring its ratio in relation to its parent uranium-234. Now, the daughter isotope thorium-230 is an isotope of the element thorium. And on the surface of the earth theres a lot of thorium floating around, which includes some thorium-230, but which isnt the daughter of the local uranium but is, rather, there because its been carried in the form of detritus. So, watch out! What if some of this detrital thorium-230 gets into your sample? Well, if it gets in there it will make the sample look older because, basically, the higher the thorium-230 contentor in relation to uraniumthe older is the sample. So, we needed to correct for this.
And I guess the people who got me interested in this was the people from Lamont, back in the 1960s, I suppose, particularly a guy named Dave Thurber who was doing a Ph.D. thesis on trying to date uraniumuranium series dating of something. He wasnt really doing uranium series dating at all; he was just measuring uranium disequilibrium of things. But he suggested the idea of a kind of an isochron plot, and so this is what we picked up on. And I think a number of different people were trying to develop isochrons at about this same time.
Alf Latham, who was my graduate student and then later became a postdoc with me, he and I turned to this problem and we kind of wrote a couple of papers, which were called Dirty Calcite. Actually, we wrote one paper called Dirty Calcite, and then a Polish postdoc I hadworked with me later, uh, his name was[I cant] remember his name. It was a very complicated name, [Wojciech] Przybylowicz. Przybylowicz and I and Alf Latham tested this out experimentally by creating dirty calcite artificially from clean calcite plus dirt, and we showed that you could construct isochrons from these mixtures, which gave the correct age for the clean component, which was kind of neat.
All right, so this techniquewe applied it, first of all, to the site that I mentioned before, Vrtesszlls, and we were able to come up with a date for this sitewhich, by the way, was radically younger than the date that the
HS: geomoprphologists wanted it to be. And this is one of the really weird stories of my life. [It] is that this paperthe people working on Vrtesszlls published a symposium or
BO: Proceedings [of a symposium].
HS: Proceedings volume called The Archaeology of the Site of Vrtesszlls, which included two papers by us: one by Alf, principally by Alf, on the paleomagnetics of the sediments showing that they were normalthe normal orientation. And the second was uranium series date of the travertines, and of course, it came up with this veryfor them, very young age. And in the paper on the uranium series dating there was a footnote added by the editor saying, The editors have been chosen to include this paper, even though they do not believe the results presented in it.
HS: (laughs) And you can see that if you look up the volume on Vrtesszlls, yes.
Okay, so, um, Alf and I did this work, and then from that point on this opened up a whole different area of investigation, which was trying to date stalagmitesor not stalagmites, but speleothems from situations where there might be a lot of detritus present. And this turns out to be a very common problem in archaeological sites because people drag a lot of dirt into the caves with them. In fact, the significant amount of the detritus in some caves is probably the result of humans living in the caves, and that detritus gets mixed up with the speleothems, particularly flowstone, since theres not much current washing the flowstone surface so it just acquires this stuff. And so, this makes a real messy problem, but we could get through it by multiple analyses. Of course, it means that to get one date you now have to do four or five or more uranium series analyses, but the method did seem to work out.
BO: Be accurate by the end.
HS: But later on, or just a little bit after this time, a guy named [James] Bischoff working at the U.S. Geological Survey, and also Teh Lung KuRichard Ku [as we call him].
BO: Oh, and Fitzpatrick.
HS: Yeah, Fitzpatrick. They
HS: They also worked on this problem, and they were able to do slightly more elegant solutions that I think
HS: Polishing it, and I think, really, the finalin the final analysis, the best approach was this method calledso-called total dissolution method, in which you dissolve everything, the calcite and the detritus, and mix them all together and analyze them all in one run. And that might give you the most accurate method; but even now, to this day, Im not convinced as to whether this is the right approach.
And then theres another aspect of this thing, which was developed by a guy named Ken Ludwig, whos at thewas at the Geological Survey and now is at the Berkeley Geochronology Lab in Berkeley, California. And Ludwig showed that you could optimize the analysis by using a certain kind of statistical procedure, which allowed the error on both the X and the Y axes to be free, because usually you assume one variable is independent and the other is dependent. So, you minimize the error on one and maximize the error on the other, and he showed that there was another kind of software you could useanother kind of statistics you could use, which would give you a better statistical evaluation.
Okay, so this is again getting a little bit far away from the main stream, but this was, I would say for me, a very interesting period of working on the dirty calcite problem. And perhaps the last place that we applied this thing to was not really a karst situation at all, but these were carbonate sediments that were forming in paleolakes in the middle of the Sahara Desert that I worked on with a guy from Texas named, uh, oh, God (laughs)what is this? [Fred Wendorf] Uh, anyway, itll come to me. Yes, anyway, (laughs) paleolakes.
Okay, so, uh, where am I? I think Im going to skip overwell, do you want me to talk about ESR dating? Is itI think this is kind ofits kind of marginal to the karst story and it really is more about archaeology in general.
BO: Itsyeah, its more archaeology. I remember there were some studies that were [done] trying to do speleothems.
HS: Okay. Yeah, Ill talk to you about that. Okay.
HS: Lets talk a little bit about ESR. Okay, ESR. What does that stand for? Thats electron spin resonance dating; and this is a methodwell, electron spin resonance is a method of analysis that was developed by the chemists to look at what are mostly called free radicals in organic substances, but its a way of detecting the presence of an unpaired electron in a crystal or a material of any sort.
And sometime in the early eighties [mid-1970s], I guess, a Japanese scientist named Motoji Ikeya began to be interested in using ESR as a method of dating. And the first material he tried dating, oddly enough, was a stalactite. Now, why he picked out a stalactite, I dont know, (laughs) but I guessed he figured it was a nice pure substance and it was some calcite crystals, and he seemed to be getting some kind of an age from it. So, he then turned to some archaeological sites to do this on, and which archeological site did he go to? None other than Petralona, the very same site which we had been dating by U-series. And so, he got some supposed dates from there. Im notI dont even remember what kind of numbers he got from there, but it seemed as if it would be possible to determine the age of a stalagmite by electron spin resonance, anyway.
So, in the 19lets saywhat year wouldve that been? Hmm, I actually dont even remember. I think its in the period right after I was in Israel on sabbatical doing ESR dating; that would have been in the early eighties [1980s]. When I came back to Canada I was starting to do ESR dating on teeth from archaeological sites. But also, I thought we should try going back to stalagmites, since stalagmites were my first love for dating; and, besides which, we knew so much about them; and, besides which, we could tell what age they were supposed to be, so we could compare the ESR date to the U-series date. And so, I had a graduate student at that point from Greece, whose name was Jake Karakostanoglou. Unfortunately, Jake was not able to continue in the scientific discipline because he had a family business which he had to take over in Piraeus, Greece. The last I knew, he was living in Piraeus and
BO: Doing something else.
HS: Doing something very unscientific. But at any rate, I gave him the task of constructing an isochron. Now, the idea of an isochron is that in ESR dating you have two variables that are very important. One is the dose rate, and the other is the dose. The dose rate is the rate at which radioactivity is bombarding the crystals and generating little trapped electrons, and then the dose is the amount of trapped energy which has been built up in the stalagmite.
So, it seemed to me that with a stalagmite you had the posswell, with aparticularly if youre looking at stalagmites, you had the interesting possibility that you had variable uranium concentration and that meant that you had variable dose rate and, therefore, you could make a graph of the signal intensity versus the dose rate, uranium concentration, and use this to calculate the age, because basically the slope of that line would depend upon the age. The uranium, once it gets into the stalagmite, stays there forever, and the only thing which is changing the radioactivity is the U-series growth of the thing. So, you can sort of correct for the fact that there was some uranium series growth and then you can make a correlation.
So, we did that and we publishedwe wrote a paper on this thing, which we actually ended up publishing in some rather obscure journal, it seems to me. It was published in PACT, which wasas a journal it doesnt even exist anymore.
Journal of the European Study Group on Physical, Chemical, and Mathematical Techniques Applied to Archaeology.
It was a journal which was almost entirely populated by articles by people doing either thermoluminescence dating in those days, or later on a little bit of ESR, but mostly thermoluminescence dating. So, you wont even find this journal, PACT. You wont find it in your library anywhere; and probably I should go back and get this paper and republish it somewhere else than a journal, because its still basically the right story but it disappeared from view.
And interestingly enough, I presented this at a conference on thermoluminescence dating, because in those days the only people who were interested in these kinds of methods were really using this other technique called thermoluminescence andoh, and by the way, you can also use thermoluminescence to date speleothems, it turns out, though I never ever tried to do that. Some other people did, but I didnt go that route.
So, this showed that in theory it was possible to date speleothems by ESR, and then (laughs) along came Rainer Grn and his supervisor at the University of Cologne, in those days, who was Professor Brunnacker. And they tried to do ESR dating on speleothems, and they crashed in flames, so to speak. It didnt work. It wasnt working at all.
BO: But he has a lot of papers, I think.
HS: No; he has a lot of papers, subsequently, on ESR dating in other things.
HS: But his first attempts were trying to ESR date stalagmites and it was definitely the wrong thing to date, and it took them a few years of failed experiments to find this out. Maybe we were lucky with our isochron dates, and we were just working on the very few samples that actually did have good, uh
HS: Signals, and didnt suffer from the problems that other samples did. And I wouldnt even say we know today what the problem really is, but its probably most likely due to a well known difficulty in the general field of physics, which is fading, which is the notion that once the signal is formed by trapping electrons that the electrons have some tendency to disappear, to become retrappedto be untrapped and then retrapped where you dont see them, and then the signal just drops away with time. And that could be the explanation, though that would always give you signals which were too young; whereas in fact some of their data were giving samples which were too old, and they were just all over the place. They were upsy-downsy, upsy-downsy.
So, the ESR dating of stalagmites had a short and (laughs)short life. Every now and then, Derek would keep coming back to me and saying, Listen, why dont we try dating this stuff by ESR since its too old to date by U-series? and I would have to take him to the Faculty Club and buy him another beer and say, Derek, you know, ESR really doesnt work on stalagmites. Lets try not to do that anymore. Anyway (laughs), so, that was it.
Okay, now I think were going to move briskly on to the later part of the twentieth century and the early part of the twenty-first century.
HS: And come back to fluid inclusions, and then I think thats going to bring an end to my
HS: Okay, because Im really going on a bit too much. Sometime aroundoh I dont know when. Sometime in the late nineties [1990s], perhaps, a group at the University of East Anglia, Tim Atkinson in particular and Peter Rowe
BO: Peter Rowe, yeah.
HS: got interested in the idea of going back to the old fluid inclusion story, and together with another guy whose name I should know very well, but it justoh, God, again. [Paul Dennis]
BO: I have it in my mind myself.
HS: Okay, yeah, right. Actually, he was the key ingredient to this, because he designed the equipment. He built this marvelous magnetically operated crusher that would crush stalagmites in a vacuum system and then liberate the water, and then they proceeded to analyze this mass spectromerymass spectrometrically, but they also analyzed the oxygen. And in their opinion, it was possible tofirst of all, using this machine that it was possible to get very good D measurementsvery good, lets say, plus or minus a certain error. And also, they could measure the 18O, and they did this on some Holocene stalagmites, but they really didnt publish any paleotemperature data based on it.
But at this time I had a studentDerek and I had a student named Freda Serefiddin, and wed gotten back into the speleothem game after a bit of a lapse and then we thought well get Freda to do the fluid inclusion stuff. So, she actually learnedI think she went to East Anglia, and she saw the equipment in operation and then she got the design for it and brought it back. And we constructed one of these things and it worked, and then she did some analyses and published one paper, at least, in a special paper of the Geological Society of America [Bulletin]. But you could see in this paper that there were huge errors in the very poor replication in serial samples of the same material, and this worried me.
And then at about the same time, my old friend in Jerusalem, Alan Matthews, was starting to do fluid inclusions by decrepitation, which is a totally different method where you take the sample, heat it up in a flame and then the water comes off and you collect the water in ajust by cooling the tube downstream. And he was getting reasonably good values, but they were offset by about 20 from the correct value that he knew to be.
So, itI dont know; sometimes I would lay awake at night trying to think of how to do things better, you know. And one night, one sleepless night, I got this idea and I said, Theres a thing called the mean free path. If a water molecule is moving around in vacuum, it has a very long mean free path, and theres a pretty good chance that its just going to keep going until it runs into something solid like the wall of the crushing chamber, and if it gets there its going to stick.
So, what you want to do is you want to get something standing in its way so it cant run into the wall of the chamber. [It] cant run into anything until you get it to the place where you want it to sit down, and so what you do is put other things in its way in the form of helium atoms. So, what if we passed a stream of helium through the crushing chamber while it was being crushed, and this would whisk the water molecules away from the crushed calcite before they had a chance to settle down anywhere. And so, Freda had finished her thesis, [and] by this time it was too late for her to do anything.
By this point, a new student came on line, who was Ren Zhangand hes just graduated, really, so were really up to the very recent times. And my technician in the lab, Martin Knyf, and Ren and I constructed this new line with a pipe on the top of the crusher, which carried the stream of helium into the system, and after some false starts we discovered that we could reproduce the D value of a fluid inclusion with a precision of about 0.1.
BO: Oh, yeah, thats great.
HS: Yeah, which is really pretty damn good considering how little water you have to work with. And so, from that point on I realized now we have a thing we can actually make use of. So, in the last five years or so, essentially, weve been applying this to measure Holocene paleotemperatures, and thats really where were up to right now. And the papers, in fact, just in press in Geochimica, and that is, you might say, the last word on the subject up to now. And Im not going to tell you, since this is only a recording of past history and not future history, where were going to go to next
BO: Its secret?
HS: because God knows if any of that will work. Right.
BO: Yeah, science is unpredictable!
HS: Yeah. Okay, so I think thats it from the mental records of Henry Schwarcz, but Im sure you might have some other questions for me.
BO: Well, yes, I was just curious. Is thewell, I know that you got rid of [the] alpha spectrometer, but you have a TIMS or ICP now?
HS: Oh, God, yes! Oh, I forgot entirely about TIMS. Oh, right. Oh, thank you for reminding me about that. Yes. Ah! Right.
Larry Edwards, in
HS: What isno, no. Well, first of all, Caltech.
HS: There is a guy at Caltech who has to be remembered in this whole business named Gerry Wasserburg. Now, everyone knows Gerry Wasserburg; he was the man on the moon. He washe built the Lunatic Lab at Caltech for the analyses of returned lunar specimens. But he washe is, was, and is possibly the most brilliant scientist ever to work in earth sciences; he could do anything.
At any rate, so amongst other things, sometime in the 19what?eighties [1980s], I guess, he got the idea that since he had these very high precision mass spectrometers that he could measure the age of corals more precisely than anybody had ever done before by using mass spectrometry to measure thorium-230 and U-234. Now, dating of corals has nothing to do with karst as such, but because the chronology problem is exactly parallel to that of stalagmites, namely determining ages in the Pleistocene, there is obviously a very important feedback through here.
So, he had a student named Larry Edwards, and really, it was Larry and Gerry and Dimitri Papanastassiou who developed the U-series dating method using
BO: Mass spectrometry.
HS: Mass spectrometry. Now, we refer to this as TIMS. This is thermal ionization mass spectrometry. The difference being that the sample, instead of being vaporpassed through the system as a gas, as we do for oxygen isotopesis loaded onto a filament and evaporated from the filament at a high temperature .
Now, the next storypart of the storyis that Larry Edwards went to Minnesota, set up a TIMS lab there, and began dating everything under the sun. But at about the same time, we had a graduate student named Li. I cant remember what his first name is, but he was a very fine young man; [he was] a Chinese national who came to us to do first a masters degree, which he did on something involving radioactive waste disposal, and then he started to do a Ph.D. And for his problemfor his Ph.D. problemwe gave him the problem of applying TIMS dating to stalagmites. And so, he worked with Joyce Lundberg, who was at that time working with Derekshe was really Dereks student, not mineas a graduate student working on stalagmites and flowstones in caves in the Bahamas, I guess, or in some
BO: Yeah, in the Bahamas.
HS: In the Bahamas. And, uh
BO: Was it Ko?
BO: Li Ko?
HS: Uh, no, no. He wasLi was his last name, but I, uh
BO: Yeah, cause I know they have a paper of the first mass spectrometer date coming to date on the Bahamas.
HS: Yeah, okay, okay, okay. So, what happened was that Li, working together withBob McNutt at this time was our head honcho on doing thermal ionization mass spectrometry, and we were using a homemade mass spectrometer, in fact, for doing this. It was built at the machine shop that built all the other mass spectrometers at McMaster, but it worked fine. It was a great little mass spectrometer.
He was using it mostly for strontium isotopes, but we fixed it up to use it for U-series dating, and we got measurements that were surprisingly precise; I mean, way, way more precise than we could ever get by alpha spectrometry. And then, later on, Joyce and Derek published a much more detailed paper on the dating of a particular flowstone from the Bahamas that had Stage 5e record, sea level record, in it. I didnt even mention any of the stuff about the blue holes and the, uh
BO: Sea level changes.
HS: Sea level change. Well, theres not enough time to talk about everything, but you know, how much can I talk.
Anyway, so TIMS came along at that point as the great white hope, the great new discovery, and so we proceeded to train, or retrain, our alpha spectrometer technician, Nicki Robinson. She stopped doing alpha spectrometry and she started doing TIMS dating, and it was marvelous because she could get dates with a precision of about 1 percent, which was sort of what Larry Edwards was getting. Sometimes it wasnt quite as good as that, but other times, it would be even better than that, and we never looked back.
That was about the point that the alpha spectrometer took their vacation tothey went on sabbatical to Romania.
HS: And then we kept doing that until about two years ago, and I guess what reallyyeah, maybe about two years ago. The end of the story is that I began to see the writing on the wall because first of all, it was taking Nicki Robinson a very long time to do each TIMS analysis, and time is money. You know, we were having to spend that much time getting herpaying her salary. And, in the meantime, a new method had come online, which was multicollector ICP-MS, and so, I was beginning to get the feeling that we shouldoh, and also the other thing which was happening [which] was very important was that Derek, who had really been paying Nickis salary laterally and doing a lot oftaking in a lot of others peoples samples for analysis, that Derek was retiring and his NSERC grant was running out, so we couldnt afford to keep her. So, the lab basically shut down.
HS: Leaving us without a really viable way of doing uranium series dating for a while. So now, thanks to having a little bit of money in our research grant and the fact that other people can now do uranium series dating for us for about as much as it wouldve cost us to do then ourselves, we can keep doing this.
BO: Well, yeah. The good thing with McMaster and with you and with Derek and with others is that you dont only create a school or people who are very well educated, but all these guys brought over and overtheir knowledgeand they continue the school, but some of them move into business but not so many
HS: Some of them, but others of them kept moving and going off and doing
BO: Yeah, and Iyou know, you just
HS: Well, look at Stein-Erik [Lauritzen]. You know, I dont know what happened to Stein-Erik when he was
BO: Hesyeah, hes doing okay. Not that good like [a] few years ago when his lab was populating and lots of money.
BO: But thats something else. But what Im looking [at] is that if you go into the karst environment, I would say
BO: You will always find people, like, you know, Paul Aharon was friend with you.
HS: Yeah. (laughs)
BO: Now hes in Alabama supervising a student of mine from Romania.
HS: Yes, right, right, right.
BO: And Jack Hess, who was [with] Will White, and you know, its only a bunch of people who actually create all these lines.
HS: Yeah, but this is how science should be. You know, that there should be a few places which
BO: Focus and
HS: They seem to get stuck in doing a certain kind of thing, and then eventually that thing begins to leak out into other places.
HS: If its interesting enough. I mean, it should be interesting enough that it makes it worthwhile. Now, let me just say in closing, if I could just sort of close this thing off from the standpoint of my personal contribution, that Ive always looked upon the karst environment as being a very special kind of environment for study because nature has provided us with an almost, but not quite, closed system
HS: which is protected from all kinds of other problems that mess up the story when you go out into the outside world. And it also has provided us with a system which, at least over part of its time scale, can be very accurately dated.
What Im distressed to see today is the increasing number of people who say that theyre going to go and study isotopes and speleothems, and in theirbecause I get a lot of these grant proposals to review, and I sometimes get even papers to review, but grant proposals are what worry me the most, where they say and, We will study stalagmites from some caves. Nowhere in the papers do they mention the fact that stalagmites are extremely precious objects that, unfortunately, dont occur very often. Oh, lets say some caves are full of them, but other caves have many fewer of them, and theyre really meant to, as much as possible, to stay in the caves.
BO: Be preserved.
HS: And be preserved. And what Im afraid of is that this beautiful and precious environment will be more and more trampled on by the next generation of isotope geochemists and speleothemwell, paleoclimatologists and so on, who are not really paying very close attention to the conservation ethic of the speleothem community.
BO: Youre right here; but actually, if Im looking back, ninety-six  when Stein-Erik organizing in Bergen the first karst meeting on paleoclimate, it was one issue that was actually coming up from Peter Smart and Andy Baker.
BO: Saying, Well, we should be careful because now we have instruments. We can date very small amounts, because on the time of alpha spectrometry you never mentioned, but we needed hundreds of grams of uranium
HS: Oh, yeah, I didnt mention that. Right, yes.
BO: Okay, so now we have just milligrams to do all this, and every single meeting afterwards we try to emphasize this, but you are right.
BO: These are the karst people, not the geochemist people.
BO: Geochemist people will just go out, pick up a sample, send a student and say, Go in that cave and pick up the
HS: But its remarkable. I mean, Im not going to name any names, but I can tell you grant proposals Ive received from very imminent geochemists, who at least had their names on them, who were just talking about stalagmites as if they were like outcrops.
BO: Yeah, yeah.
HS: Its, say[like] they could, you know, go to the Rocky Mountains with their geological hammer and knock of a piece of this rock formation. Why not? Anyway.
BO: Yes. Thank you very much, Henry.
HS: All right. Youre welcome. Its been a pleasure, and I dont know if this will beI guess this will be useful for your
BO: Its going to be useful, and we have a good experience with [Alexander] Klimchouk and the other ones that we had and allit was online somewhere on our Karst Portal.
BO: And people around the world ask permission to use the portal already.
BO: Yeah, theres so much history in your story that
HS: Yeah. Now, you watch out because I mentioned some names in here, and these people are going to come back and theyd say, Wait a second, you didnt say that about me. Thats not true at all. Right.
BO: Well figure out that.
HS: Youll figure that one out, okay. (inaudible) You may have to delete that. Thank you.
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interviewed by Dr. Bogdan Onac.
Tampa, Fla. :
University of South Florida Tampa Library,
1 sound file (111 min.) :
digital, MPEG4 file +
e 1 transcript (digital, PDF file)
Karst oral history project
Interview conducted January 22, 2008 at the University of South Florida in Tampa, Florida.
Dr. Henry Schwarcz, karst scientist of McMaster University in Hamilton, Ontario, Canada, begins the interview with background information about his childhood and education. He mentions how proximity to great karst scientists and a "hot bed" of research was highly influential while seeking his undergraduate and graduate level degrees. The bulk of the interview consists of Dr. Schwarcz chronologically discussing breakthroughs in various processes for determining the age of karst samples. He details the progression in the theory of dating karst and the increasingly sophisticated scientific apparatus involved in dating karstic samples. Dr. Schwarcz closes by expressing concern over what he sees as a trend among scientists towards reduced respect for and lessened emphasis on conservation of karst environments.
Mode of access: World Wide Web.
Electron spin resonance dating.
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