Citation
The use of drought-induced crop lines as a tool for characterization of karst terrain

Material Information

Title:
The use of drought-induced crop lines as a tool for characterization of karst terrain
Alternate Title:
NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst
Creator:
Panno, Samuel V.
Luman, Donald E.
Kelly, Walter R.
Alschuler, Matthew B.
Publisher:
University of South Florida
Publication Date:
Language:
English

Subjects

Genre:
Conference Proceeding
serial ( sobekcm )

Notes

General Note:
The persistent drought of the 2012 summer in the Midwestern United States significantly impacted the health and vigor of Illinois' crops. An unforeseen outcome of the extreme drought was that it provided a rare opportunity to examine and characterize the bedrock surface and underlying karst aquifer within the Driftless Area of northwestern Illinois. Complex networks of vegetated lines and polygonal patterns, herein referred to as crop lines, crisscrossed the dry summer landscape of Jo Daviess County. Initially, the crop lines were examined and photographed using a handheld digital camera on the ground and from a small aircraft at 300 meters altitude above ground level (AGL). The orientations, widths and horizontal separations of the lines were measured. Crop lines and their patterns and orientations were compared with those of crevices in outcrops, road cuts and quarries, and with lineaments seen in LiDAR elevation data of Jo Daviess County. Primarily confined to alfalfa fields and, to a lesser extent, soybeans and corn, the crop lines are the result of a combination of extremely dry conditions, and a thin soil zone overlying fractured and creviced Galena Dolomite bedrock. The plants forming the lines tend to grow denser, taller (0.5 m vs 0.15 m) and darker/greener than those in adjacent areas. Alfalfa taproots are the deepest of the aforementioned crops extending up to 7 m below the surface. Groundwater and associated soil moisture within the vadose zone present within bedrock fractures and crevices provide the necessary moisture to sustain the overlying healthy plants, while the remaining area of the field exhibits stunted and sparse plant growth. Overall, the crop lines are a reflection of the creviced pattern of the underlying karst bedrock and associated karst aquifer, and reveal the degree and extent of karstification in eastern Jo Daviess County. The crop lines were consistent with the angular lines of adjacent streams that show a rectangular drainage pattern. Stream patterns like these are well known and are due to drainage controlled by crevice/fracture patterns in the top of bedrock. The lines appear to have been formed by two sets of fractures trending roughly north-south and east-west with occasional cross-cutting fractures/crevices. The east-west trending lines are consistent with tension joints, and the north-south lines are consistent with the shear joints identified by earlier researchers. The trends of the crop lines, tension and shear joints are similar to those of lineaments identified from LiDAR elevation data in the same area (N 20° W, and N 70° W and N 70° E) and coincide with the occurrence of karst features throughout eastern Jo Daviess County. The pattern observed in the crop lines closely mimics the fracture/crevice patterns of the bedrock surface. The widths and extent of the lines may be used as a surrogate for the karst features present on the bedrock surfaces. Crop lines, coupled with solution-enlarged crevices seen in bedrock exposures, yield a three dimensional view of the bedrock crevice-fracture system, and ultimately could provide a more complete and accurate model of the karst aquifer in the study area and similar karst areas in the Midwestern United States and perhaps in other karst regions of the world. -- Authors
Restriction:
Open Access - Permission by Publisher
General Note:
See Extended description for more information.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
K26-04789 ( USFLDC DOI )
k26.4789 ( USFLDC Handle )
11845 ( karstportal - original NodeID )

USFLDC Membership

Aggregations:
Karst Information Portal

Postcard Information

Format:
Serial

Downloads

This item has the following downloads:


Full Text
Description
The persistent drought
of the 2012 summer in the Midwestern United States
significantly impacted the health and vigor of Illinois' crops.
An unforeseen outcome of the extreme drought was that it
provided a rare opportunity to examine and characterize the
bedrock surface and underlying karst aquifer within the
Driftless Area of northwestern Illinois. Complex networks of
vegetated lines and polygonal patterns, herein referred to as
crop lines, crisscrossed the dry summer landscape of Jo Daviess
County. Initially, the crop lines were examined and
photographed using a handheld digital camera on the ground and
from a small aircraft at 300 meters altitude above ground level
(AGL). The orientations, widths and horizontal separations of
the lines were measured. Crop lines and their patterns and
orientations were compared with those of crevices in outcrops,
road cuts and quarries, and with lineaments seen in LiDAR
elevation data of Jo Daviess County. Primarily confined to
alfalfa fields and, to a lesser extent, soybeans and corn, the
crop lines are the result of a combination of extremely dry
conditions, and a thin soil zone overlying fractured and
creviced Galena Dolomite bedrock. The plants forming the lines
tend to grow denser, taller (0.5 m vs 0.15 m) and
darker/greener than those in adjacent areas. Alfalfa taproots
are the deepest of the aforementioned crops extending up to 7 m
below the surface. Groundwater and associated soil moisture
within the vadose zone present within bedrock fractures and
crevices provide the necessary moisture to sustain the
overlying healthy plants, while the remaining area of the field
exhibits stunted and sparse plant growth. Overall, the crop
lines are a reflection of the creviced pattern of the
underlying karst bedrock and associated karst aquifer, and
reveal the degree and extent of karstification in eastern Jo
Daviess County. The crop lines were consistent with the angular
lines of adjacent streams that show a rectangular drainage
pattern. Stream patterns like these are well known and are due
to drainage controlled by crevice/fracture patterns in the top
of bedrock. The lines appear to have been formed by two sets of
fractures trending roughly north-south and east-west with
occasional cross-cutting fractures/crevices. The east-west
trending lines are consistent with tension joints, and the
north-south lines are consistent with the shear joints
identified by earlier researchers. The trends of the crop
lines, tension and shear joints are similar to those of
lineaments identified from LiDAR elevation data in the same
area (N 20 W, and N 70 W and N 70 E) and coincide with the
occurrence of karst features throughout eastern Jo Daviess
County. The pattern observed in the crop lines closely mimics
the fracture/crevice patterns of the bedrock surface. The
widths and extent of the lines may be used as a surrogate for
the karst features present on the bedrock surfaces. Crop lines,
coupled with solution-enlarged crevices seen in bedrock
exposures, yield a three dimensional view of the bedrock
crevice-fracture system, and ultimately could provide a more
complete and accurate model of the karst aquifer in the study
area and similar karst areas in the Midwestern United States
and perhaps in other karst regions of the world. --
Authors



PAGE 1

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 of the underlying karst bedrock and associated karst aquifer, Jo Daviess County. The crop lines were consistent with the drainage pattern. Stream patterns like these are well known patterns in the top of bedrock. The lines appear to have been coincide with the occurrence of karst features throughout eastern Jo Daviess County. The pattern observed in the crop lines closely mimics widths and extent of the lines may be used as a surrogate for the karst features present on the bedrock surfaces. in bedrock exposures, yield a three dimensional view could provide a more complete and accurate model of the karst aquifer in the study area and similar karst areas in the Midwestern United States and perhaps in other karst regions of the world. Introduction Carbonate rock at or near the surface are fractured and typically creviced due to solution enlargement to the point Abstract The persistent drought of the 2012 summer in the outcome of the extreme drought was that it provided a rare opportunity to examine and characterize the bedrock surface and underlying karst aquifer within the Driftless Area of northwestern Illinois. Complex networks of vegetated lines and polygonal patterns, herein referred to as crop lines, crisscrossed the dry summer landscape of Jo Daviess County. Initially, the crop lines were examined and photographed using a handheld digital camera on the horizontal separations of the lines were measured. Crop lines and their patterns and orientations were compared with those of crevices in outcrops, road cuts and quarries, and with lineaments seen in LiDAR elevation data of Jo Daviess County. extent, soybeans and corn, the crop lines are the result of a combination of extremely dry conditions, and a Dolomite bedrock. The plants forming the lines tend to grow denser, taller (0.5 m vs the deepest of the aforementioned crops extending up soil moisture within the vadose zone present within bedrock fractures and crevices provide the necessary moisture to sustain the overlying healthy plants, while sparse plant growth. TOOL FOR CHARACTERIZATION OF KARST TERRAIN Samuel V. Panno Illinois State Geological Survey, 615 E. Peabody Drive, Champaign, Illinois 61821, USA, s-panno@illinois.edu Donald E. Luman Illinois State Geological Survey, 615 E. Peabody Drive, Champaign, Illinois 61821, USA, luman@illinois.edu Walton R. Kelly Matthew B. Alschuler PO Box 325, Warren, Illinois 61087, USA, matthew@cottonexpressions.com 411

PAGE 2

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE (Figure 2) occurred in the thin soils of the Driftless Area overlying the carbonate bedrock of the eastern two thirds of Jo Daviess County, the western portion of Stephenson County and well into southern Wisconsin. the crop lines observed in eastern Jo Daviess County, Illinois, and assess their usefulness as indicators of with a karst aquifer. Because the crop lines appear to accurately mimic the creviced surface of the underlying karst bedrock, we explored their usefulness in identifying the extent, character and geometry of the underlying karst aquifer. Methods The authors were contacted by a Jo Daviess County resident on July 16, 2012 concerning the appearance of crop lines in the Driftless Area of northwestern Illinois. We conducted a reconnaissance trip to eastern Jo Daviess County on July 19 during which time we examined and photographed abundant crop lines on the ground, as well The initial photography was used to secure funding for additional trips to the site. where the rock body constitutes a karst aquifer (Quinlan et al. 1991). These fractures and crevices are usually fractures and crevices in the bedrock are only observed in excavations, road cuts, quarries, outcrops and rarely where the soil and sediment overlying the bedrock where soils are thin and during extremely dry periods and where crops are planted, lines in the vegetation (hereafter referred to as crop lines) have been observed in the Wisconsin Driftless Area (Maureen Muldoon, University of Wisconsin, personal communications, 2011). It is of the underlying bedrock carbonate aquifer. Unfortunately, the reporting of these occurrences is drought conditions in Illinois and in the surrounding states in the 2012 summer created a rare situation that has resulted in the formation of vivid lines and patterns in crops in Jo Daviess (Figure 1) and surrounding counties 412 Figure 1. Generalized geologic map of Jo Daviess County (modified from McGarry 2000).

PAGE 3

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 photography. The widths, orientations and spacing of the crop lines were documented and compared with those of crevices and fractures in exposures, and with lineaments seen in LiDAR elevation data of Jo Daviess County examined and compared with information gleaned from existing bedrock exposures as described by Bradbury Results and Discussion Geology of Jo Daviess County Jo Daviess County (Figure 1) lies within the Driftless Area of northwestern Illinois; the county lacks glacial drift that covers the bedrock of most of the upper thin remnants of the Ordovician age Maquoketa shale, conducted one month later to document additional occurrences and estimate the geographic extent of the crop lines in Jo Daviess County. Based upon this information, a request was made to the Illinois Department of Transportation, Aerial Survey Division to acquire vertical aerial photography for 16 selected sites issues, aerial photographs were not taken until August 28 and 29. Soon after the IDOT aerial photography acquisition, the area experienced increased rainfall and harvesting began earlier due to the drought. The combination of these two factors resulted in the crop line features disappearing or being eliminated. probe and a tape measure. Vegetation that created the crop lines was examined on the ground and from aerial 413 Figure 2. Alfalfa fields reveal the geometry and character of the underlying karstified Galena Dolomite. Crevice-controlled rectangular stream patterns are also apparent. This oblique aerial photograph was taken 4.0 km south of Warren, IL in Jo Daviess County.

PAGE 4

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE to explain the origin of these deposits (Rowan and de Marsily 2001). Ore mineralization and dolomitization of been dated by several techniques as Early Permian in age ranging between 270 and 280 Ma (Brannon et al. 1992; Pannalal et al. 2004). Recent work by Panno et al. (in review) expanded on our understanding of the karst terrain of Jo Daviess County of the LiDAR elevation data revealed numerous been used since the early 1950s for oil, gas, and mineral exploration. Lattman and Parizek (1964) and Parizek (1976) extended this work to groundwater resources Lattman and Parizek (1964) state that Fracture traces and lineaments appear to be universal in their distribution and will have their greatest utility in rocks where secondary permeability and porosity dominate and where intergranular characteristics combine with water and groundwater movement. The lineaments in Jo Daviess County consisted of the alignment of study area. Many stream valleys are linear, while others have sharply angular meanders. These angular features or rectangular patterns are classic geomorphologic indicators and strongly suggest bedrock control of the streams in the study area (Figure 2). The lineaments in the study area have three distinct trends; approximately N20 o W, N70 o W, and N70 o E. Examination of sinkholes in eastern Jo Daviess County revealed individual sinkholes and en echelon sinkholes, all of which are coincident with lineaments. Examination of mapped lineaments in far eastern Jo Daviess County revealed that every lineament had one or two sinkholes in close proximity to one another and to the streams. Sinkholes in this area were typically 0.5 m to greater than 1 m deep and about 1 m in diameter. Larger sinkholes up to 10 m in diameter were also found. Features that were often found associated with the sinkholes were the stream bank that extended 1.6 to 5 m into the much of the highlands in the county. Tectonic compression and extension occurred in this area during and following the formation of the Wisconsin continued to be active in late Silurian or Devonian time part, separates the Illinois Basin to the south from the Michigan Basin to the east. The Mississippi River Arch separates the Illinois Basin from the Forest City Basin to the west. Jo Daviess County lies on the southwestern As a result of the compression and extension, bedrock the rock formation in the district [most of Jo Daviess o W, and two o o E and N 20 o o W. Bradbury (1959) found that crevice orientations in numerous exposures in far eastern Jo Daviess County trend N 85 o o o o W. mineralization in this area. The geology of the Upper Daviess County and extends into Iowa and Wisconsin, crevices or in solution cavities in carbonate rocks of (PbS 2 ) was the main ore mineral in these deposits, and sphalerite (ZnS 2 ) was the most abundant ore mineral associated with bedding planes and reverse faults and zinc in solution were implicated as the source of the mineralization by various geochemical and isotopic forming solutions originating from evaporative brines associated with the Reelfoot rift system (late Paleozoic time) is one of the more recent hypotheses proposed 414

PAGE 5

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 Crop Lines The 2012 summer drought that affected the health and vigor of crops of the Midwestern United States and thin soils provided an opportunity to view the geology of the underlying carbonate bedrock in the Driftless Area of Illinois. Less than 8 m of soil and unconsolidated materials overlie the fractured and creviced carbonate bedrock of Jo Daviess County, northwestern Illinois ranged from 0.6 to 1.2 m. Soil thicknesses immediately over the lines were typically greater than 1.5 m. Excavation of the lines revealed that many contained clays that were visually and texturally identical to the weathering product of Maquoketa Shale. The depth of few crevices examined. The wetness and presence of water within the clays suggested that water was moving through the crevices, perhaps along piping channels. During the 2012summer, complex networks of dark green vegetation separated by gray patches of nearly bare bank. In addition, the stream orientation tended to shift abruptly and follow the trend of the lineament where they crossed streams instead of having the more typical gently curved meanders. These angular stream features had similar orientations to the mapped lineaments and reflect bedrock control. On the basis of these data, the lineaments identified on the LiDAR maps are interpreted to be a reflection of open crevices in the underlying carbonate bedrock aquifer that are transmitting groundwater. Examination of the geomorphology of the stream valleys suggests that the lineaments are linear depressions that formed probably form where overlying sediment becomes thinner with proximity to stream valleys where carbonate bedrock is exposed in the stream floor. Lineaments in carbonate rock terrain have been found to be indicative of zones of enhanced well yields; productivity wells in carbonate terrain has had a success rate of 75 to 80% (R. Parizek, Pennsylvania State University, personal communications, 2009). 415 Figure 3. LiDAR shaded relief image of eastern Jo Daviess County showing lineaments and their orientations (from Panno et al. in review).

PAGE 6

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE rooted perennial. Upon germination, a strong taproot develops rapidly and penetrates almost vertically downward. It often reaches a depth of 1.5 to 1.8 m the and may ultimately extend to depths of 6.1 m or more. It is notably a deep feeder. Consequently, the alfalfa bedrock crevices near the top of the karst aquifer. Corn ground were observed. These lines of vegetation, often forming complex polygonal patterns with dominant sown with alfalfa, and to a lesser extent, soy beans and corn. The alfalfa forming the lines tended to grow more densely, taller (0.5 m vs on relatively steep slopes to retard soil erosion. These in September 2012 (Figure 4). 416 Figure 4. Google Earth imagery showing the complex geometry of crop lines in an alfalfa field.

PAGE 7

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 crevices. Preliminary results indicate that the crop lines are data in the same area by Panno et al. (in review). The trends springs) throughout eastern Jo Daviess County. and soybean roots tend to have shallower root systems. Corn is a more shallow rooted plant reaching depths of 1.2 m or more. Less than 10% of the water taken up by the corn plant is acquired below 1 m (McWilliams et al. 2004). Soybean plant roots extend to a depth of 1.2 to 2.4 m of soil (North Dakota State University 1997). The bedrock fractures and crevices provide the necessary moisture to sustain the overlying healthy plants, while sparse plant growth. In aerial view, the crop lines create rectangular drainage patterns. Rectangular stream patterns like these are well known and due to control Streams tend to follow the paths of least resistance. The orientation of the stream channel is consistent with the orientation of crop lines and the straight reaches of the stream follow trends seen in crevices exposed in outcrops, road cuts and quarries (Figure 5). This and the similarity of crop lines with lineament patterns in LiDAR elevation data, and crevice occurrence in outcrops, road cuts, and quarries found throughout eastern Jo Daviess County, western Stephenson County, and northern Carroll County indicate that the lines and of the creviced pattern of the underlying karst aquifer. As crevices of the underlying carbonate bedrock and reveal of Jo Daviess County. Finally, desiccation cracks are almost exclusively located along the crop lines and follow their trends (Figure 6). lines where vegetation was stunted and typically about 6 inches high. This phenomenon is probably due to fact that the shallow roots of the crops tend to take up moisture from the soil and create desiccation cracks, but only in those areas were vegetation is thriving. Ongoing Research The authors are currently georeferencing and analyzing sixteen sites in eastern Jo Daviess County, and their 417 Figure 5. Road cut through Galena Dolomite and located along Rt. 20 near Elizabeth, IL in Jo Daviess Co. The solution-enlarged crevices are oriented N-S and are 1 m wide (from Panno et al. in review). Figure 6. Desiccation cracks within and following the trends of the crop lines.

PAGE 8

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE exposed in outcrops, road cuts, and quarries, and of lineaments seen in LiDAR elevation data of the study area. Crop lines, combined with other data from outcrops, road cuts, quarries and LiDAR elevation data, may be used to identify and characterize the degree and extent Area on northwestern Illinois, and other karst areas of similar geology. Further research currently is underway. Acknowledgements We thank Jeff Kromer of Mount Carroll, IL for the generous giving of his time, skills and aircraft while in order to acquire reconnaissance aerial photography. Finally, we thank Amy Eller of the Illinois Department of Transportation for contributing the Aerial Survey Division resources to acquire the vertical aerial photography in a timely manner. References Survey Report of Investigation 210. 49 p. Brannon, J.C., F.A. Polosek and R.K. McLimans. 1992. Alleghenian age of the Upper Mississippi Valley In Geology of Illinois (D.R. Kolata and C.K. Nimz, Jr. 1959. The geology of the upper Mississippi U.S. Geological Survey Professional Paper between fracture traces and the occurrence of Soybean growth and management quick guide. from: Nelson, J.W. 1995. Structural features in Illinois. Illinois North Dakota State University. 1997. Corn production Available from: Based on the presence and orientations of the crop lines in road cuts, quarries, and outcrops, and lineaments seen in LiDAR elevation data, it is clear that the patterns of the bedrock surface. The widths and extent of the lines may be used as a surrogate for the karst features present on the bedrock surfaces. Crop lines, coupled with bedrock exposures, yield orientations and spacing carbonate bedrock. Taken together, these features yield system, and ultimately could provide a more complete and accurate model of the karst aquifer in the study area and similar karst areas throughout the world. Conclusions An investigation of crop lines that appeared during the extreme drought of the 2012 summer in the Midwestern United States may provide an additional method for investigating and characterizing karst terrains. The crop lines were noticed by local farmers primarily in alfalfa Within days, the crop lines on the ground and from aerial photography. The widths, orientations, and distance of separation of the lines were examined and compared with crevices in outcrops, road cuts and quarries, as well as with lineaments observed in LiDAR elevation data. and composition of the materials within the crevices. The crop lines formed in very shallow soils (less than about 1.5 m thick) and are of similar orientation as those cuts, and quarries, and of lineaments seen in LiDAR beneath the thin soils contained clays similar to those of weathered Maquoketa shale. It is likely that these clays clay suggests there is piping and movement of recharge and groundwater through the clay. We conclude that the crop lines may be used as a the carbonate bedrock surface. The crop lines are of 418

PAGE 9

13TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 2 Pannalal, S.J., D.T.A. Symons and D.F. Sangster. 2004. Paleomagnetic dating of Upper Mississippi Valley fracture traces and lineaments in carbonate and Publications, Fort Collins, CO. Jr., A.J. Edwards, A.R. Smith. 1991. Recommended aquifers, practical evaluation of vulnerability of karst aquifers, and determination of optimum sampling frequency at springs. Proceedings of thickness of Quaternary deposits, Jo Daviess Weibel, C.P. and Panno, S.V. 1997. Karst terrains and Survey, Illinois Map Series 8, 1:500,000 Scale. 419

PAGE 10

NCKRI SYMPOSIUM 2 13TH SINKHOLE CONFERENCE 420