Cave Notes

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Cave Notes

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Title:
Cave Notes
Series Title:
Caves and Karst: Research in Speleology
Alternate Title:
Caves and karst: Research in speleology
Creator:
Cave Research Associates
Publisher:
Cave Research Associates
Tumbling Creek Cave Foundation
Publication Date:
Language:
English

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Subjects / Keywords:
Geology ( local )
Genre:
Newsletter
serial ( sobekcm )

Notes

General Note:
Planes of repose in caves / Arthur L. Lange. Cave Notes(vols. 1-8) and Caves and Karst: Research in Speleology(vols. 9-15) were published by Cave Research Associates from 1959-1973. In 1975, the Tumbling Creek Cave Foundation compiled complete sets of the journals in three volumes. The Foundation sells hardbound copies of the material to support its activities.
Restriction:
Open Access - Permission by Publisher
Original Location:
Tumbling Creek Cave Foundation Collection
Original Version:
Vol. 5, no. 6 (1963)
General Note:
See Extended description for more information.

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University of South Florida Library
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University of South Florida
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Resource Identifier:
K26-00648 ( USFLDC DOI )
k26.648 ( USFLDC Handle )
13719 ( karstportal - original NodeID )
0008-8625 ( ISSN )

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PAGE 1

CAVE NOTES A Review of Cave and Karst Research Volume 5, No, 6 November/December, 1963 Figure 1. Water-level horizons in Bower Cave, California. PLANES OF REPOSE IN CAVES by Arthur L. Lange, Cave Research Associates The successive shapes of cave walls subjected to uniform solution can be determined for any arbitrary initial configuration (Lange, 1959). For example. a completely s ubrne r-ge d passage rectangular in cross-section bec o rne s in time, rounded at its corners; whereas. a square projecting ledge remains square as its sides retreat. If the passage is only partly submerged (as in the case of a cave lake), the underwater portion of the walls recede, producing flat planes--water-level planes--at the air/water interface (Lange, 1962). The process involves unifor-m solution below a certain level, but no solution (and consequently no wall retreat) above that level. The present report considers the inverse case of uniform solution above, but not below a given boundary or slope angle. In nature, the process corresponds to the accumulation of insoluble residues and detritus, fornring barriers to normal solvent action on floors and sloping walls of submerged portions of caves. 41

PAGE 2

CAVE NOTES CAVE NOTES CAVE NOTES is a publication of Cave Research Associates and the Cave Research Association. Subscriptions are available for $ 2.00 per year (six issues) or on exchange, Mid-year subscriptions receive the earlier numbers of the volume. Correspondence, contributions, and subscriptions should be addressed to: CAVE RESEARCH ASSOCIATES, 3842 Brookdale Blvd, Castro valley, Calif. Editor: Arthur L. Lange, Cave Research Associates Associate Editor: Ronald A. Brandon, Cave Research Association (Dept. of Zoology, Southern Il11nois University, Carbondale, Illinois) ~mnaging Editor: R. deSaussure, Cave Research Associates. @) Copyright 1963, Cave Research Associates. In this introductory study, we limit our considerations to two-dimensional cave cross-sections and impermeable sediments, realizing that these are only convenient idealizations. We do not treat the problem of tracing shapes back to their original forms, nor the effects of sedimentation on accrescent forms such as flows tone and stalagmites, but defer these subjects to later studies, The simplest case is that of the vertical cave pas sage, which has become partly sediment-filled, so that solution proceeds only agains t the bare wall (FA in Figure ZA). No sediment is accumulating. If the fill is immobile and insoluble, the point A serves as an infinitesimal cylinder, and the wall and floor dissolve radially around it (see LANGE, 1959, p. 73), while the vertical wall retreats in parallel stages, forming the contour BCDE. 1£ the fill is at all mobile (the more likely case), it migrates into the trough, preventing its development; thus, only parallel wall retreat can take place. The resultant form, once exposed (as by draining and flushing), would be the wall and shelf BCAE of Figure lB. A similar argument applies in Figure ZC: again a trough is unlikely to form in the case of mobile fill, so that the inclined wall retreats parallel to itself, forming the wall and shelf BCAE. In Figure ZD, the overhanging wall retreats everywhere uniformly; the floor point A enlarges as a cylinder radially, and a trough is unlikely if the fill is mobile. The example of Figure 2E is almost trivial; in effeet, a completely filled passage does not dis solve, It is important to bear this in mind when comparing the dimensions of different cave passages. The formation of these shelves can occur in partly filled caves which become r e -eubme r-ged. If fill is in part preserved by cementation, it betrays the origin of the shelves. Bretz (1942) cites examples from an underground stream in Mark Twain Cave, Missouri. :Vhen sedimentation proceeds concurrently with solution, a veneer of s e diment accumulates on all slopes whose angle from the horizontal is less than a. certain critical value (t (Figure 3A). Angle a is characteristic of pr-ope rttes of the accumulating particles such as cohesion roundness and epbextcity: an~ of the texture of the wall' and the velocity of the fluid which be.ars the sediment, This angle is analogous to the angle of repose of detrr-ttus on ,slopes cut -of-doo r s For purposes of this paper, we may regard .the depos-its to be of one kind (say, Silt), forming under similar conditions 42

PAGE 3

VOLUME .5, NO. 6 in all cases, so that angle a remains constant. In the diagrams, I have arbitrarily chosen a to be 45¡. Thus, submerged walls of steeper angles remain bare and continue to dissolve, while silt collects on all slopes of It or lower angles, and they cease to dis solve. The critical slope of Figure 3A has accumulated a veneer of silt, and so cannot dissolve. The initially curved wall ABC of Figure 3B cannot di s solve below B, at which point the slope angle is It; above B the wall recedes normally until a segment of the critical plane is achieved. This plane-segment extends upward from point B, as the bare portions of the wall retreat. This type of inclined planar wall is hereafter called a Elane Qf ~p'ose. A good illustration is provided by Figure SA, which shows two facets of such a wall, one of which remains covered by its protective silt coating. Another example is shown in Figure 5B. Planes of repose are common at both sites. The initial structure of Figure 4A is a circular tube. Undergoing solution it expands everywhere above the points of tangent It. Since no slope of lesser angle can form, the plane of repose is extended progressively. From the diagram, one can see that the tendency is toward an inverted triangular shape. In Figure 6, a circular tube occurs above an elliptical tube. Both dissolve according to the rules just explained. Eventually they coalesce, after which the retreating ceiling of the lower portion consumes the lower edges of the upper planes. The photograph of Figure 5C may be explained in this way. Some "keyhofe'' passages arise in this way. The solid half-cylinder of Figure 4B is exposed to solution and sedimentation with interesting results. Unlike the same corner in Figure ZA, accumulation prevents any such low-angle slope from forming; instead, point A must be regarded as a segment of a small circular cylinder that behaves as the cylinder of Figure 4A, forming a plane of repose AB. The walls from A to C are initially steep enough to recede normally; from C upwaa-ds a B D F B -:......-:::... _I.=: :::=-1:::: .::: = -::t =_-=-:IC:: :::= --1--::r_. -----,-I~ =--=.-=--::1'= ---:A:-i:C ;:.".::;".::~ 1::A c E Figure 2. Retreat of walls in partially filled passages after sedimentation ceases. Initial wall FAE, designated by solid contour, retreats through dashed contour to become the form BeE (necnured}. Sediment represented by dots, dissolving water by dashed lines. ThiS symbolism is maintained in all diagrams of the report. !!.. Vertical plane wall, immobile f111; !!. Same, mobile fill; g. Inclined plane wall, mobile fl11; Q.. Overhanging plane wall, mobile fill; ,!. Completely filled passage. 43

PAGE 4

CAVE NOTES ~-=E====_==':_~=D -==-=-=--=:=-1-':: --=-=-= =-=-~,--r:--:-=-=-=--=-=~J... E ------Ji... Sedimentation hinders solution on wall of slope angle 0< or less. !!.. CircuLar tube sector ABC develops plane shelf BE of slope angle 0<.. A silt veneer prevents solution. At C, however. an infinitesimal cylinder di s solves radially. thus undermining the upper surface [cf Figure 7G). In Figure 7, various co rnbi nati ons of slopes are examined. Nowhere does a positive slope more gentle than the critical slope form; initially-gentle slopea, however, are preserved unless undermined as in Figure 7G. In 7H, both walls are too steep for silt to accumulate. The imaginary cave passage of Figure 8 illustrates the combining of initial forms and their behavior under solution with sedimentation. It is, admittedly, an artificial example, but its tendency to form perpetuating planes cf repose brings to mind many sketches in the author's field notebooks, from which I have s e-, lected examples in Figure 9. In nature, the planes almost consistently show A B Figure 4. Solution of circular cylinders during sedimentation. A. Hollow tube. Initially circular tube (solid contour) enlarges radially through all walls steeper than angle 0<. Plane of repose extends upward from ini t1al points of tangent 0<'". ~. Solid cyHnder (partial). Initial contour ACD retreats normally except above point C (at tangent 0<), where sediment protects the wall. Point A behaves as infinitesimal cylinder (cf., Figure 4A), developing plane of repose. At point C, a similar small tube begins dissolving radially, unde r-m'im.ng slope CD. Line FCE is the tangent through C; CG, its normal. 44

PAGE 5

VOLUME J, NO, 6 45

PAGE 6

CAVE NOTES traces of the veneer that brought them about; in many cases, the veneer is reinforced with calcite. Most collections of cave photographs contain examples of planes of repose, 80 that the reader may supplement my evidence from his own albums and bookshelf. Karl Gripp (1912) encountered plane sloping walls in the Segeberge gypsum caves. He explained these II Ltlsungsfazetten" (solution-facets) to be the result of solution in a concentration gradient. Thus, the less concentrated zone of the fluid near the surface was said to dissolve more rapidly than that of the lower parts. His mechanism might be possible undel' nearly stagnant conditions in extremely soluble rock, but it would not explain the multitude of planes on all levels in limestone caves whose scalloped walls and gravel deposits attest to an active circulation of solvent during formation. An interesting combination form arises when a plane of repose intercepts a water-level plane (Lange, 1962). The latter is e a ai.Ly visualized in the left-hand wall of Figure 10, where solution is confined to the zone below water level. With sedimentation proceeding, however, planes of repose commence from 45¡ slopes, and these extend gradually upwa.r-ds toward the water level. In principle, the two types of planes meet at an acute angle, but due to agitation of the sediment by wave action near the surface, the lower plane is likely not to reach quite all the way. Also, fluctuations in water level may shift the wat.e r-c-Ieve l plane up and down around its mean to make the overall form imperfect. The resulting incision is a type of 'trdp'' that I term a water-level horizon, or, within context, simply horizon. Nips rnay arise by other mechanisms in outdoor situations (Kaye, 1959), but I believe that the explanation outlined above will account for almost all examples in dissolved limestone caves. Horizons have typically flattish visors, rounded inside corners, and sloping shelves. To be valid examples, they Figure 6. Coalescence of circular tube lying above elliptical tube during s edfmenation. P T_ '"==-,~ ~:f_ ~-:-_-::r=-. _.-----A r___ '"1-_ ::-1:-, -~ --,-I:':, ==-=:I~ --= ==-=:t B E F =.-'::-:: -r=-===l~: --1-----y c D '1--"-I=-'1=-' ..:J:-, =:::-1-:::Ii =--""'=-=:-:::' ----------=---------------=--/5.-0.--=--1-:..\-...:~_-E: ~_ _ i-_lii._-,c-'_ G H Fig~re 7. Wall retreat of simple initial structures during sedimentation, showing development of planes of repose. 46

PAGE 7

VOLUME .s I NO. 6 Figure 8. Evolution of a hypothetical cave passage during submergence wi th sedimentation. Symbolism as in Figure 2, with water shading omitted. should be concordant with other horizons and water-level planes in the s ame chamber and cave. There may be, of course, a vertical series of horizons and water-level planes, corresponding to successive water levels. The ahe Ive e should contain evidences of sediment. A well-known display of horizons occurs in Bower Cave, California. The upper portion of Bower Cave is a large collapsed chamber whose positivesloping walls are sculptured into a series of horizons up to two meters in depth (Figures I and 5D; and Cave Studies, 1959: frontispiece). Their shelves contain silt, sealed by flowstone and overgrown by mos s On overhanging walls. the horizons are matched by water-level planes, which can be traced upward to the ceiling window as ancient water levels. A deep pool, 33 meters below the ceiling connects underwater with interior chambers of great beauty. The pool level fluctuates lea s than 1/2 meter and has produced some imperfect horizons around its mean (Figure 11). Skin divers have reported horizon-like structures at water level in the interior chambers. Cave of the Quills and Sink Cave, Calaveras County; one of the White Chief Caves and Paradise Cave, Tulare County; Cave Man Cave, Tuolumne County; Alabaster Cave, Eldor-ado County; and Rippled Cave, Amador County are a few additional caves in California that exhibit excellant examples of water-level horizons and planes of both types. Planes of repose have also been recognized by R. deSaussure in Cave of the Domes, in the Redwall limestone of Grand Canyon National Park in Arizona. I ., A. (_ " """,,:" -. :-~'!: " )1 .I~-'!r2' B Figure 9. Examples of planes of repose containing clay remnants. A. Samwel cave, California; ~. Drug Store Cave, Missouri. Both sections approximately 3 meters high. 47

PAGE 8

CAVE NOTES Figure 10. Origin of water-level horizons. Partially submerged cave chamber with sedimentation develops typical planes of repose under water, and water-level planes at water line. The two forms coalesce, producing horizons. With changing water-level stands, a series of horizons can form, one above the other, as in Figures 1 and 5D. References: BRETZ, J HARtEN. Vadose and phreatic features of limestone caverns. Journal Q Geology, voi.. 50, no. 6, p 675-811. 1942. GRIPP, KARL. tiber den Gipsberg und die in Lhm vorhandene HOhle. Hamburg wt saenschaftliche Anstalten, Jahrbuch 30, Seiheft 6, s 35-51. 1912 KAYE, CLIFFORD. Shoreline features and Quaternary shoreline changes, Puerto Rico. !l.&. Geological Survey, Professional tgp.er 317B, HOp. 1959 (see also review in Cave Notes, vot 2, no. 5, p 36-39. 1960). LANGE, A. L. Introductory notes on the changing geometry of cave structures. Cave Studies, no. 11, p 69-90. 1959. LANGE, A. L. 1962. Water level planes in caves. Cave Notes, vo L, 4, no. 2, p.12-16. Figure 9. Horizons near water line, Bower Cave, California. 48


Description
Planes of repose in caves / Arthur L. Lange.
Cave Notes(vols. 1-8) and
Caves and Karst: Research in Speleology(vols. 9-15)
were published by Cave Research Associates from 1959-1973. In
1975, the Tumbling Creek Cave Foundation compiled complete
sets of the journals in three volumes. The Foundation sells
hardbound copies of the material to support its
activities.


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