EXAMINATION OF AN ABANDONED UNDERGROUND LAKE IN THE SCOTT
HOLLOW DRAINAGE BASIN, SOUTHEAST WEST VIRGINIA
A Thesis
Presented to
The Graduate Faculty of The University of Akron
In Partial Fulfillment
of the Requirements for the Degree
Master of Science
James Nii Kamuah Addo
May, 2009 EXAMINATION OF AN ABANDONED UNDERGROUND LAKE IN THE SCOTT
HOLLOW DRAINAGE BASIN, SOUTHEAST WEST VIRGINIA
James Nii Kamuah Addo
Thesis
Approved: Accepted:
______Advisor Dean of the College Dr. Ira D. Sasowsky Dr. Chand Midha
______Faculty Reader Dean of the Graduate School Dr. LaVerne M. Friberg Dr. George R. Newkome
______Faculty Reader Date Dr. John A. Peck
______Department Chair Dr. John P. Szabo
ii ABSTRACT
The research studied a subterranean sediment deposit in an abandoned underground passage and soils from a sinkhole within the Scott Hollow drainage basin,
Monroe County, southeast West Virginia. The purpose was to decipher how the abandoned underground lake formed, and the origin of the deposited sediment.
Two excavations were made in the sinkhole overlying the eastern portion of the cave and a total of 11 samples were collected there for study. 174 meters of total cave passage was mapped to delineate the morphology of the cave and to calculate passage volume as well as the volume initially covered by sediment and the current volume of sediment in place. Five different profiles were subsequently made from four sediment terraces in the cave, and 32 sediment layers were sampled. Grain size and environmental magnetic analyses (magnetic susceptibility, frequency dependence, anhysteretic remnant magnetization, isothermal remnant magnetization) were conducted on all collected samples. A composite stratigraphic column of the subterranean sediments was also constructed in an attempt to establish the depositional sequence.
The results indicated that the overlying soil types form part of the Teas-Calvin-
Litz and Frederick-Duffield-Dunmore soil associations. The cave survey showed that lake was formed as a result of partial conduit blockage by damming of the stream from the release of breakdown blocks when the ceiling of the cave collapsed. 517 m3 of fluvial
iii sediment was then deposited, of which 64% (331 m3) has since been eroded, leaving a present volume of 36% (i.e., 187 m3). There is currently 1398 m3 of open passage volume. The deposition was from two major hydrologic – depositional cut and fill phases resulting to the four sediment terraces (two lower terraces and two upper terraces).
The lower terraces are younger than the upper terraces, as evidenced by the lower sediments lapping onto the upper terrace. Channel and wall irregularities and the breaching of the dam resulted in irregular deposition and erosion of the sediment.
The environmental magnetic studies showed high magnetic mineral concentrations, abundant superparamagnetic grain fractions, and both low and high magnetic coercivity minerals. Correlation of the magnetic mineralogy, however, showed the subterranean sediment to be composed of high coercivity minerals (goethite) and the soils composed of low coercivity minerals such as magnetite. Although correlation of soils and cave sediment was not possible based on magnetic mineralogy, there existed a general correlation between the layers of sediment found within the stratigraphic column constructed from the cave sediment.
The morphology of the cave and the sediment present substantiate the fact that sediments were deposited due to partial conduit blockage from the damming of the stream. The grain size analyses indicate that studied samples are mainly of clay, silt, sand, pebbles and some cobble size fractions. Gravel mineralogy is shale and chert.
Shales in the sediment and the cave wall are both fine grained and smooth in texture, with light – dark gray to greenish gray coloration. This is different from shales found in the soils which have light-gray color (by visual inspection). Based on these findings, it can therefore be argued that gravels found in the cave sediment did not originate solely from
iv outside the cave. The color of the samples was determined in-situ. This may have led to apparent differences in color due to variable moisture conditions. Therefore the hypothesis that the cave sediments were derived from a sinkhole overlying the eastern environs of the cave could not be substantiated because of the imprecise correlation established between the cave sediment and the sinkhole soils. The cave sediments are likely autochthonous at least in part.
v ACKNOWLEDGEMENTS
I would first like to thank Dr. Ira D. Sasowsky for all of his guidance and suggestions throughout the project. Next, I would like to thank my committee members
Dr. L. Friberg and Dr. John Peck for their help on all of the additional edits. Next I would like to thank Thomas Quick and Dr. John P. Szabo for the support they gave me in analyzing my samples in the laboratory. Although Thomas Quick and Dr. John Szabo were actually not part of the conglomerate of advisors I had, their contributions toward the achievement of the research goals were overwhelming. I would also like to say thank you to Elaine Butcher for all the support she rendered. Finally, I would like to thank my wife Mrs. Emma Addo, my family back home and all my friends for the kindest support and encouragement they gave me during these hard times. God bless you all.
vi TABLE OF CONTENTS
Page LIST OF TABLES ...... xi
LIST OF FIGURES ...... xiii
LIST OF PLATES ...... xix
CHAPTER
I. INTRODUCTION ...... 1
1.1 Purpose of Study ...... 1
1.2 Sedimentation in Caves...... 3
1.3 Location and Overview of the Study Area ...... 4
1.4 Hydrogeology of Study Area ...... 7
1.5 Preliminary Description of Deposit in the Cave ...... 10
1.6 Description of Soil Types Found in the Study Area ...... 10
1.7 Previous Local Studies of Cave Sediment ...... 12
II. METHODOLOGY ...... 14
2.1 Introduction ...... 14
2.2 Field Methods ...... 14
2.2.1 Sampling of Sinkhole Sediments ...... 14
2.2.2 Cave Survey ...... 17
vii 2.2.2.1 Survey of Cave Passage ...... 18
2.2.2.2 Survey of Sediment Deposit ...... 18
2.2.3 Descriptive Stratigraphy and Sampling of Lake Deposit ...... 19
2.3 Laboratory Methods ...... 22
2.3.1 Grain Size Analysis...... 23
2.3.1.1 Measuring Procedure ...... 23
2.3.1.1.1 Methodology ...... 23
2.3.1.2 Treatment of Grain-Size Data ...... 25
2.3.2 X-Ray Diffraction (XRD) ...... 26
2.3.2.1 Bulk Sample Mineralogy ...... 26
2.3.2.2 Clay Mineralogy ...... 27
2.3.3 Magnetic Parameters of Sediment Samples ...... 28
III. RESULTS ...... 30
3.1 Sinkhole ...... 30
3.1.1 Lithology and Mineralogy on Soil Profile SH-Soil-1 ...... 30
3.1.2 Lithology and Mineralogy on Soil Profile SH-Soil-2 ...... 35
3.1.3 Organic and Magnetic Measurement on SH-Soil-1 and SH-Soil-2 ...... 38 3.1.4 Discussion ...... 50
3.2 Cave ...... 54
3.2.1 Cave Survey ...... 55
3.2.2 Stratigraphic Description of Lake Deposit ...... 59
3.2.3 Magnetic Measurements on Cave Sediments ...... 78
3.2.4 Volume of Sediment Deposited and Removed ...... 86 viii 3.2.5 Discussion ...... 91
IV. DISCUSSION ...... 98
4.1 Correlation of Lake Sediments and Sinkhole Soils Using Measured Magnetic Characteristics ...... 98
4.2 Analysis Based on Percent Grain Size Content ...... 99
4.3 X-Ray Diffraction Analysis (Bulk and Clay Mineralogy) ...... 102
4.4 Correlation of Deposit using Magnetic Mineral Characteristics Quantitatively ...... 104 V. SUMMARY AND CONCLUSION ...... 107
REFERENCES ...... 113
APPENDICES ...... 117
APPENDIX A. RESULTS OF X-RAY DIFFRACTION ANALYSIS ON SH-SOIL-1 AND SH-SOIL-2 ...... 118
APPENDIX B. GRAIN SIZE DATA FOR SH-SOIL-1 ...... 123
APPENDIX C. GRAIN SIZE DATA FOR SH-SOIL-2 ...... 124
APPENDIX D. MAGNETIC PARAMETER DATA TABLE FOR PROFILES SH-SOIL-1 AND SH-SOIL-2 ...... 125
APPENDIX E. CAVE PASSAGE SURVEY STATISTICS AND MEASURED DATA ...... 130
APPENDIX F. XRD AND GRAIN SIZE DATA FOR CAVE SAMPLES...... 132
APPENDIX G. CAVE SEDIMENT MAGNETIC DATA ...... 147
ix APPENDIX H. STATISTICAL GRAIN SIZE DATA AND KEY FOR INTERPRETING ENVIRONMENTAL MAGNETIC RESULTS FOR SH-SOIL-1, SH-SOIL-2 AND DEPOSITED CAVE SEDIMENTS ...... 150
APPENDIX I. TABLE OF THE SURVEYED STATIONS, ELEVATION OF STATION AND THE FLOOR OF THE CAVE AT THE STATION ...... 197
x LIST OF TABLES
Table Page 1 Soil analysis showing percentage of grain size fractions for profile SH-Soil-1 ...... 32
2 Soil analysis showing percentage of grain size fractions for profile SH-Soil-2 ...... 35
3 Measured values from detailed surveying of cave passage and cave sediment deposit in Chris’ Trunk ...... 56
4 Sediment analysis showing percentage of grain size fractions for profile JNA-1A ...... 60
5 Sediment analysis showing percentage of grain size fractions for profile JNA-1B ...... 64
6 Sediment analysis showing percentage of grain size fractions for profile JNA-1C ...... 68
7 Sediment analysis showing percentage of grain size fractions for profile JNA-2...... 72
8 Sediment analysis showing percentage of grain size fractions for profile JNA-3...... 75
9 Calculated areas and volumes of passage, current upper terrace deposit and, eroded upper terrace deposit ...... 92
10 Minerals identified in sinkhole samples using XRD ...... 102
11 Minerals identified in cave sediment samples using XRD ...... 103
12 Correlation of sediment by comparing their magnetic characteristics quantitatively...... 105
xi 13 Comparison of the North and South sediment terraces ...... 107
14 Gravel mineralogy for cave deposit ...... 112
xii LIST OF FIGURES
Figure Page
1-1 Sediment age relative to cave age and position ...... 5
1-2 U.S. and state map showing location of study area with respect to the boundary of the Appalachian Plateau and Valley and Ridge physiographic provinces. Original from Shank (2002) ...... 6
1-3 Generalized stratigraphic section of the middle to late Mississippian Greenbrier Group in Greenbrier and Monroe Counties. From Shank, 2002, after Heller, 1980...... 8
1-4 Topographic map showing location and orientation of Scott Hollow Cave. Modified from Hochstetler (2005), original from Mike Dore. Contour interval = 20 foot ...... 9
1-5 Photograph of the lake sediment deposit. View is downstream (westward). In addition to bedded, non-indurated alluvial sediments, breakdown blocks from ceiling collapse are also present ...... 11
2-1 Detailed map showing portions of Scott Hollow Cave (Dore, 1994) in relation to topography (USGS, 2000) and sample locations. 20 foot contour interval ...... 15
2-2 Photograph showing total sections of excavated columns of profiles SH-Soil-1 and 2 and the respective locations within the sinkhole plain. View looking North with scale in centimeters (cm) ...... 16
2-3 Cored soil sample showing uppermost 16 centimeters of the profiles SH-Soil-1 and 2 respectively ...... 17
2-4 Photograph showing paleomagnetic sampling process...... 20
2-5 Photograph showing sampling from the upper terrace of southern deposit, profile JNA Section 1B...... 21
xiii 2-6 Plan view sketch showing cave, sediment deposit, location of dam, and stream direction ...... 22
2-7 Chart showing treatment of samples for grain-size analysis ...... 24
2-8 Flowchart showing treatment of samples for environmental magnetic measurement ...... 29
3-1 Cross-Section of profile SH-Soil-1 ...... 31
3-2 Ternary plot of sediment grain sizes from profile SH-Soil-1 based on percentage of grain size fractions. See Appendix B for data. Modified from Folk (1980) ...... 33
3-3 Variation in grain size with depth for profile SH-Soil-1. See data in Appendix B...... 34
3-4 Cross-Section of profile SH-Soil-2. No top soil present due to thin grass cover over the first soil layer ...... 36
3-5 Ternary plot of samples from profile SH-Soil-2 based on percentage of grain size fractions. See data in Appendix C. Modified from Folk (1980) ...... 37
3-6 Variation in grain size with depth for profile SH-Soil-2. See data in Appendix C...... 38
3-7 Magnetic concentration and lithologic parameters measured on core SH-Soil-1. Magnetic concentrations are high at depth greater than 70 cm. See Appendix D for data ...... 39
3-8 Magnetic concentration and lithologic parameters measured on core SH-Soil-2. Concentration of magnetic minerals decrease generally with depth on χ, SIRM and ARM plot as % organic content of sample decreases See Appendix D for data ...... 40
3-9 Grain-size dependent and mineralogic parameters measured on core SH-Soil-1. (a) Smaller SP grain-sizes are shown between depths 62 – 88 cm, as well as an increase in small modal grain sizes. (b) Biplot of χfd % versus χlf showing origin of dominant domains. See Appendix D for data ...... 42
xiv 3-10 Grain-size dependent and mineralogic parameters measured on core SH-Soil-2. (a) Smaller SP grain-sizes are shown with increasing in depth, (b) Biplot of χfd % versus χlf shows origin of magnetic mineral and dominant domains. See Appendix D for data ...... 43
3-11 Plot of normalized ARM values against AF demagnetizing field for select soil samples. Samples at shallow depth decay faster compared to samples collected from deep depth. See Appendix D for data ...... 45
3-12 Plot of normalized IRM values against AF demagnetizing field for select soil samples. Decay trend suggest the presence of MD grain sizes in all samples. See Appendix D for data ...... 46
3-13 Graphs of normalized ARM and IRM on select samples from core SH-Soil-1 and SH-Soil-2. See Appendix D for data ...... 47
3-14 IRM acquisition plot on pilot samples. There is an increase in concentration of magnetic minerals with increase in depth. See Appendix D for data ...... 48
3-15 DC demagnetization of IRM values on pilot samples. See data in Appendix D ...... 49
3-16 Mineralogy plot of samples from core SH-Soil-1. (a) Organic content, S-ratio at (-100 and -300), and HIRM with depth. (b) Biplot of SIRM/χ versus ARM 40 mT/SARM. (c) Biplot of IRM -100 mT/SIRM versus ARM 40 mT/SARM. See Appendix D for data ...... 51
3-17 Mineralogy plot of samples from core SH-Soil- 2. (a) Organic content, S-ratio at (-100 and -300), and HIRM with depth. (b) Biplot of SIRM/χ versus ARM40 mT/SARM. (c) Biplot of IRM -100 mT/SIRM versus ARM 40 mT/SARM. See Appendix D for data ...... 52
3-18 Plan view map of the surveyed cave passage of Chris’ Trunk. Figure shows the survey stations, relative location of the upper and lower terraces of the deposited sediment, the dam and stream flow direction ...... 57
3-19 Three dimensional passage model of Chris’ Trunk. Yellow markers are stations, and elevations are shown in different colors. Inset show the plot at different orientation ...... 58
3-20. Cross-section of Chris’ Trunk showing location of profile JNA-1A ...... 59
xv 3-21. Ternary plot of samples for profile JNA-1A based on percentage of grain size fractions. See Appendix F for data ...... 61
3-22 Grain size plot for profile JNA-1A. See Appendix F for data ...... 62
3-23 Cross-section of Chris’ Trunk showing location of profile 1B...... 63
3-24 Ternary plot of samples for profile JNA-1B based on percentage of grain size fractions. See Appendix F for data ...... 65
3-25 Grain size plot for profile JNA Section 1B. See Appendix F for data...... 66
3-26 Cross-section of Chris’ Trunk showing location of profile 1C...... 67
3-27 Ternary plot of samples for profile JNA-1C based on percentage of grain size fractions. See Appendix F for data ...... 69
3-28 Grain size plot for profile JNA Section 1C. See Appendix F for data...... 70
3-29 Cross-Section of Chris’ Trunk showing location of profile JNA-2 ...... 71
3-30 Ternary plot of samples for profile JNA-2 based on percentage of grain size fractions. See Appendix F for data ...... 72
3-31 Grain size plot for profile JNA-2. See Appendix F for data ...... 74
3-32 Cross-section of Chris’ Trunk showing location of profile JNA-3...... 75
3-33 Ternary plot of samples for profile JNA-3 based on percentage of grain size fractions. See Appendix F for data ...... 76
3-34 Grain size plot for profile JNA-3. See Appendix F for data ...... 77
3-35 Magnetic mineral concentration graphs (susceptibility, ARM and SIRM) for profile JNA-1A. See Appendix G for data ...... 79
3-36 Magnetic grain size graph for profile JNA-1A showing frequency dependence of susceptibility, ARM/ , SIRM/ARM and SIRM/ versus depth. See Appendix G for data ...... 79
3-37 Magnetic mineral concentration graphs (susceptibility, ARM and SIRM) for profile JNA-1B. Mineral concentration fluctuates with depth along profile. See Appendix G for data ...... 80
xvi 3-38 Grain size graph for profile JNA-1B showing frequency dependence of susceptibility, ARM/ , SIRM/ARM and SIRM/ versus depth. See Appendix G for data ...... 81
3-39 Magnetic mineral concentration graphs (susceptibility, ARM and SIRM) for profile JNA-1C. Mineral concentration fluctuates with depth along profile. See Appendix G for data ...... 81
3-40 Grain size graph for profile JNA-1C showing frequency dependence of susceptibility, ARM/ , SIRM/ARM and SIRM/ versus depth. See Appendix G for data ...... 82
3-41 Magnetic mineral concentration graphs (susceptibility, ARM and SIRM) for profile JNA-2. Mineral concentration fluctuates with depth along profile. See Appendix G for data ...... 82
3-42 Grain size graph for profile JNA-2 showing frequency dependence of susceptibility, ARM/ , SIRM/ARM and SIRM/ versus depth. See Appendix G for data ...... 83
3-43 Magnetic mineral concentration graphs (susceptibility, ARM and SIRM) for profile JNA-3. Mineral concentration fluctuates while depth along profile. See Appendix G for data ...... 84
3-44 Grain size graph for profile JNA-3 showing frequency dependence of susceptibility, ARM/ , SIRM/ARM and SIRM/ versus depth. Value of sample 3-L6, 7 & 8 is influenced by presence of diamagnetic mineral. See Appendix G for data ...... 85
3-45 Normalized ARM versus AF demagnetizing field for cave samples. See Appendix G and plate 3 for data ...... 87
3-46 IRM versus magnetizing field. See Appendix G and plate 4 for data ...... 88
3-47 Normalized IRM demagnetize curve versus AF demagnetizing field. See Appendix G and plate 5 for data ...... 89
3-48 Normalized IRM demagnetize curve versus DC demagnetizing filed. See Appendix G and plate 6 for data ...... 90
3-49 Diagram showing inferred deposition and erosion of lake sediments ...... 93
xvii 3-50 Photograph showing the channel that has now breached the base of the dam ...... 94
3-51 Photograph showing onlapping feature between upper and lower terrace of the Chris’ Trunk sediments ...... 95
4-1 Plot of soils from the sinkhole based on grain size distribution. Shaded regions show soil categories along the profiles ...... 100
4-2 Plot of sediments from Chris’ Trunk based on grain size distribution. Shaded regions show sediment categories along the profiles ...... 101
5-1 Longitudinal profile of thalweg showing deposits...... 109
xviii LIST OF PLATES
Plate
1 Topographic map of study area showing Scott Hollow Cave, Greenbrier River and Second Creek. Black dots are other cave entrances. Modified from Demrovsky (2003) and Balfour (1991).
2 Diagrammatic cross-sections of Chris’ Trunk at survey stations 0, 5, 10, 5, 20, 25, and 30 meters (not drawn to scale). Sections show the relative positions of lake deposit, stream, and the open passage. 12 measurements labeled “X” were made with tile probe, other measurements with laser rangefinder. View from west to east.
3 ARM AF demagnetization on cave sediments.
4 IRM acquisition for cave sediments.
5 IRM AF demagnetization on cave sediments.
6 IRM DC demagnetization on cave sediments.
7 Composite stratigraphic column from Cave deposit. Graphs show magnetic mineral concentration and mineral grain size and how these parameters vary in the individual sediment layers.
8 Summary diagram showing correlation of stratigraphy along with grain size and magnetic results. Correlation is based on gravel mineralogy of sediment and quantitative comparison of their measured magnetic mineral characteristics.
9 Flow Sheet for Clay Mineral Identification.
xix CHAPTER I
INTRODUCTION
1.1 Purpose of Study
The evolution of a cave is influenced by the amount of surface water entering the ground overlying the cave, the type of rocks and their structure in and around the cave, the dissolved materials contained in the water as it enters the cave, and the environment of the cave. As surface waters enter the cave, they can transport sediments and deposit them as water velocity reduces. The sediment ending up in the cave is therefore capable of documenting the episodes and the regional or local environmental conditions that contributed to their deposition.
Studies that document the action of surface water, transportation, and deposition of sediments have been conducted by several researchers. For example, Springer and Kite
(1997) examined a river-derived slackwater sediment in the caves of the Cheat River canyon (West Virginia) in connection with the Cheat River flooding that occurred in
November 1985. They were able to establish that sediments deposited by the November
1985 flood lie within 1 m of the established high water mark and are good indicators of peak stage. Also, deposits that are shielded from significant runoff are more well preserved than deposits that encounter the actions of cave streams which actively remove sediments. In another study, Mahler et al. (1999) demonstrated that mobile sediments in a karst aquifer can exhibit a range of properties that affect their contaminant transport
1 potential by studying the geochemical characteristics of cave sediments. The study of sediment deposits in caves will therefore be useful for understanding the geomorphology and morphology of the caves in relation to streams around their catchments.
This present study examines an abandoned underground lake in Chris’ Trunk, a large conduit in Scott Hollow Cave, West Virginia. The work tested the hypotheses that the abandoned underground lake was formed due to a dam of breakdown that resulted in partial conduit blockage, and that the sediments found in the cave are from a sinkhole overlying the eastern portion of the cave. To address these hypotheses, field observations as well as mapping of cave and sediment deposit were conducted to establish the processes that lead to the formation and abandonment of the underground lake. Unlike river systems whose sediments could result from different sources (slopes and river banks), a dendritic cave system usually allows sediment to be traced to a surface sinkhole. Laboratory analyses were done on samples taken from 5 locations within the lake deposit and 2 profiles excavated within the soils found in the sinkhole east of the cave to assist essentially with the evaluation of sediment characteristics and comparison between the lake sediment and soils, to see if the origin of the cave sediment is decipherable.
This study will give clues on the formation of the lake and help understand the present-day and paleo-hydrologic processes taking place in the Scott Hollow drainage basin. The cave sediment deposit provides a unique opportunity to study stratigraphy and hydrology simultaneously, in order to understand the transport and storage of sediments through the cave.
2 1.2 Sedimentation in Caves
Caves are formed where there is limestone bedrock which becomes karstified. As plant and animal matter decay in the top level of soil, micro-organisms involved in the process release carbon dioxide gas. Rain water and sinking streams that come in contact with the soil react with the carbon dioxide to form a weak carbonic acid solution. As water carrying carbonic acid travels through fractures in bedrock, it dissolves some limestone thereby enlarging the discontinuities. This initiates a continuous reaction that eventually dissolves more limestone (about 25 times more) than would dissolve in water alone (White, 1988).
Sinking streams may flush sediment down the surface openings into an aquifer and therefore serve as a source by which sediment might be carried into the aquifer.
Secondarily, water infiltrating through the overlying soils of the aquifer may contribute soils to these sediments through vertical movement (Bosch and White, 2004). These sediments (allochthonous in origin) are transported further in the karst aquifer where they may accumulate. Transportation of this sediment is episodic with abrupt movements during storm flow and little movement during low flow conditions (Bosch and White,
2004).
The accumulated magnetic characteristics in cave sediment might result from soils or sediments that have been transported from the surface and chemical precipitation.
These soils or sediments normally have enhanced magnetic parameters which result from surface processes such as warmer climate (such as warmer interglacial stages) and its corresponding enhanced pedogenesis (Ellwood, et al., 1998; Evans and Heller, 2003).
Also, as base levels are lowered, entire flow paths in the karst are often abandoned,
3 resulting in higher elevation, dryer and ancestral cave passages. This sediment preserves the characteristics associated with the depositional regimes. Inference can therefore be made from the lithologic and stratigraphic study of these sediments concerning the hydrologic history and source from which they were deposited. Also, in a network of conduits or stretch of caves underneath a sinkhole plain, a stratigraphic study of accumulated sediments can be used to determine the relative ages and how sequentially the caves developed with the oldest sediment at the highest elevation as shown in Figure
1-1 (Sasowsky et al., 1995). Such study of deposits in caves can also be used as a tool for reconstruction of past climate as demonstrated by Asrat et al. (2006) and Polk et al.
(2006).
1.3 Location and Overview of the Study Area
Scott Hollow (Figure 1-2), is located in southeastern West Virginia (Monroe
County), on the transitional margin between the Appalachian Plateau and the Valley and
Ridge geomorphic provinces (Ogden, 1976). The bedrock exhibits numerous folds with gently inclined limbs and many sinkholes (Davis, 1999). There exists only minor surface drainage within the region, with most runoff entering sinkholes and then flowing through an extensive karst aquifer. Scott Hollow Cave, which underlies Scott Hollow, forms part of that flow system, and is currently in a vadose condition. The deeply entrenched
Greenbrier River to the north provides base-level drainage.
The drainage basin can be separated into three levels encompassing approximately 500 meters of topographic relief: the river valley, the sinkhole plain
(known as the Big Levels), and the surrounding hills.
4
Figure 1-1. Sediment age relative to cave age and position (from Sasowsky et al.,1995).
5 West Virginia
0 200
km
Figure 1-2. U.S. and state map showing location of study area with respect to the boundary of the Appalachian Plateau and Valley and Ridge physiographic provinces. Original from Shank (2002).
The tops of the surrounding hills are capped with clastic rocks of the Bluefield
Formation (Heller, 1980).
Scott Hollow Cave has more than 50 kilometers of mapped conduit (Dore, 1995).
It has a depth of 174 meters and is ranked the 13th longest cave in the United States
(Gulden, 2006). The cave occurs in the Middle-Late Mississippian limestone of the
Greenbrier Group (Figure 1-3), which is approximately 240 meters (800 feet) thick
(Heller, 1980) in the area. The lower bounding unit of the cave is the Mississippian
Maccrady Shale which is calcareous (Ogden, 1976). This is a relatively resistant unit and serves as the base for the formation of many conduits. The overlying Hillsdale Limestone is the primary unit for Scott Hollow Cave. It is described by Reger (1926) as a shaly limestone, alternating with minor to massive limestone beds. The Sinks Grove Limestone lies directly above the Hillsdale Limestone and comprises massively bedded, fossiliferous limestone containing an abundance of chert (Ogden, 1976).
6 The bedrock is variably folded, based on structural study of cave passages
(Ogden, 1974; Davis, 1999). The rocks generally strike about S25°W, dipping 10° to the northwest (Heller, 1980). A study of the Ludington Cave which is located in the eastern part of the Appalachian Plateau and lies within Greenbrier County, West Virginia
(Palmer, 1974) documents that more than 60% of the cave developed along a limestone/shale contact. There exists also a strong correlation between stratigraphic dip and conduit orientation in this area (Davis, 1999).
1.4 Hydrogeology of Study Area
Scott Hollow Cave forms a branch network under both vadose and phreatic conditions and is generally oriented in the north-south direction and parallel to strike, along Flat Top Mountain. Tributary conduits connect to the main north-south conduit from the westerly direction against dip (Figure 1-4), and from the east following dip.
These subsurface tributaries join the main passage which contains the Mystic River as a principal stream. The Mystic River flows for 8.5 km (5 miles) from South to North within
Scott Hollow Cave (Dore, 1995). Underground drainage pathways can be controlled by faults, joints and folds, however, the flow of streams through this cave are mainly controlled by the orientation of bedding. The surface drainage sub-basin is bounded to the north and northwest by the Greenbrier River (Jones, 1997), and to the west by Flat Top
Mountain (Plate 1). The plateau contains only one surface stream, Second Creek, and other drainage is funneled into sinkholes. Allogenic runoff from Flat Top Mountain recharges Scott Hollow Cave via a few short western tributaries.
7
Figure 1-3. Generalized stratigraphic section of the middle to late Mississippian Greenbrier Group in Greenbrier and Monroe Counties. From Shank, 2002, after Heller, 1980.
8
Mystic River
Figure 1-4. Topographic map showing location and orientation of Scott Hollow Cave. Modified from Hochstetler (2005), original from Mike Dore. Contour interval = 20 foot.
9 1.5 Preliminary Description of Lake Deposit in the Cave
The sediment studied in this research is deposited in Chris’ Trunk, a part of the
Scott Hollow Cave network (Figure 1-4). The sediment contains very little moisture, however, a narrow stream transects the deposit. The deposit has been truncated into two terraces by this stream. The well preserved portion of the deposit measures about 2 meters in thickness and 30 meters in length along the dip of bedrock. The deposits are laid against a wall of breakdown blocks which have formed from the collapse of the ceiling blocks (Figure 1-5).
The deposits therefore appear along the banks of the narrow present day stream which is currently flowing in a westward direction.
1.6 Description of Soil Types Found in the Study Area
Soils overlying the cave are likely to come from two soil associations which are the Frederick-Duffield-Dunmore and Teas-Calvin-Litz association. The following three paragraphs on the soil associations are summarized from the county report by the United
States Department of Agriculture (1965).
The Frederick-Duffield-Dunmore association is subdivided into three broad series, which are the Duffield, Dunmore, and Frederick series. However, the cave has a catchment which excludes the Dunmore series from contributing sediments to the lake deposit. The Duffield soils are known to form from strongly sloping to steep, well- drained soils on rolling uplands, which developed under hardwood forests in material weathered from the silty strata in the Greenbrier Group limestone. This gives soils which are relatively leached, yellowish-brown coloration, porous, and soft.
10
Bedrock ceiling
Sediment Deposit Breakdown bedrock blocks
Figure 1-5. Photograph of the lake sediment deposit. View is downstream (westward). In addition to bedded, non-indurated alluvial sediments, breakdown blocks from ceiling collapse are also present.
11 They are strongly acidic with dark grayish brown silt loam surface, and the subsoil yellowish-brown silty clay or clay. They generally have low organic-matter content and high moisture-holding capacity, and occur in the broad limestone valley in the north-central part of Monroe County with association to the Frederick soils.
The Frederick soil types are extensive in the broad limestone valley occupying the north-central part of the county. They develop under a cover of hardwood in weathered material from the Greenbrier limestone, and have very friable surfaces, which are dark grayish-brown cherty silt loam or silty loam. The subsoil is reddish-brown to red, silty- clay to clay. The acidity varies from being strongly to moderately acidic.
The Teas-Calvin-Litz association comprises the Teas series and the Teas-Calvin-
Litz complex. The Teas series consists of shallow to moderately deep, well-drained, friable, reddish-brown soils that are developed in materials weathered from acidic and weakly calcareous reddish shale siltstone of the Mauch Chunk and Maccrady Formations.
The surface layer is reddish-brown silt loam and the subsoil is reddish-brown heavy silt loam to silty clay loam. Below this, lies a reddish shale that contains thin, widely spaced calcareous lenses and seams. The Teas-Calvin-Litz complex soils, however, are dominantly silt loam and very stony silt loam. They have moderate permeability and low to moderate moisture holding capacity.
1.7 Previous Local Studies of Cave Sediment
Sediments in the caves of this area have been the focus of earlier study. Haney,
(2002) studied sediments in the tourist area of Scott Hollow Cave and established that
“the cave possesses a complex environment with many factors affecting its equilibrium system and this complexity has resulted in high concentrations of magnetic materials
12 indicative of iron oxyhydroxide chemical precipitation”. A study of sediment from
Windy Mouth Cave which is just North of Scott Hollow, by Curry (2002), showed that gravels in that cave were derived from units within the Maccrady Formation of the
Greenbrier Group, and were of allogenic and autogenic origin. These gravels contain an average of 66% chert. Grain sizes between 2.0 mm to 1.0 mm varied from very angular to very rounded in shape, with the sub-rounded shape being dominant in chert grains. Shale and siltstones clasts were sub-rounded to rounded.
Shank (2002) noted that coarse sediments in Windy Mouth Cave are generally poorly sorted and occasionally imbricated, and therefore represent high discharge flow regimes that probably originated from a sinking stream. Fine grained deposits, however, are laminated clay and silt that were deposited under calm conditions.
Hochstetler (2005) studied sediments from four different caves (Hunt Cave, Scott
Hollow Cave, Union Cave and Organ Cave) in the area. Some of the sediments within each cave could be roughly correlated from different passages based on evaluation of individual magnetic parameters. Most sediment, however, possessed low concentrations of magnetic materials with magnetic susceptibility values below 100 × 10-8 m3/kg. The sediments contained mixed mineral grain sizes that included superparamagnetic types
(evidence from the grain size and mineralogy parameters measured).
Using magnetic polarity reversals, Hochstetler (2005) concluded that the sediment contained in Scott Hollow Cave was deposited within the past 780,000 years due to the lack of magnetic reversals
13 CHAPTER II
METHODOLOGY
2.1 Introduction
This section of the thesis focuses on the field and analytical methods employed in the study. The field methods included surveying of the cave passage and cave sediment and sample acquisition. Samples were also collected from the soils found in the sinkhole overlying the eastern upstream termination of Chris’ Trunk.
2.2 Field Methods
This section of the write up details the field techniques employed to collect samples, the measurements made in the field, and the procedures used in the laboratory to measure parameters of interest.
2.2.1 Sampling of Sinkhole Sediments
In this study, two surface excavations were made to expose the underlying soils for sampling using a mini engine powered excavator (Skid Steer Loader) within the sinkhole closest to the upstream termination of Chris’ Trunk. The area is labeled in
Figure 2-1. These excavated profiles; labeled SH-Soil-1 and SH-Soil-2 are positioned along the topography such that SH-Soil-1 is located at the lowest point in the sinkhole, and SH-Soil-2 is partway up the sloping wall of the depression.
14
in relation to
(Dore, (Dore, 1994)
20 foot contour interval. contour 20 foot
s of Scott Hollow Cave and sample locations. sample and
) (USGS, 2000 (USGS,
Detailed Detailed map showing portion topography
1. - Figure 2 Figure
15 These are separated by a distance of about 150 meters and represent the different soil associations found within the sinkhole plain i.e. the Frederick-Duffield-Dunmore and
Teas-Calvin-Litz associations. The constructed vertical profiles, SH-Soil-1 and SH-Soil-
2, from the column of soils exposed, were labeled such that SH in the labeling scheme serves as an abbreviation for Scott Hollow and Soil-1 and Soil-2 serve as the first and second soil profiles respectively. The full extent of the profiles was measured using a measuring tape (Figure 2-2), and the respective thicknesses of soil layers were determined.
SH-Soil-1 0 cm SH-Soil- 2
0 cm 50 cm
Sinkhole 50 cm
Figure 2-2. Photograph showing total sections of excavated columns of profiles SH- Soil-1 and 2 and the respective locations within the sinkhole plain. View looking North with scale in centimeters (cm).
16 About 1 kg of soil sample was collected in Ziploc plastic bags from each distinct soil layer using clean plastic materials, and sealed tight to prevent contamination or sample loss. The samples were labeled top to bottom with the authors initials and the soil layer sampled such as JNA Soil 1-Layer 1. The layer numbering was successively increased until all layers from a profile have been sampled. This procedure resulted with
9 layers for profile JNA Soil 1 and 3 layers profile SH-Soil-2.
Two core samples were also taken from the respective soil exposures by pounding a 1.5 meter PVC pipe through the soil with a rubber mallet. The surrounding of the pipe was dug and the pipe and its contents removed (Figure 2-3).
Top Bottom Top Bottom
Figure 2-3. Cored soil sample showing uppermost 16 centimeters of the profiles SH- Soil-1 and 2 respectively.
2.2.2 Cave Surveys
The cave surveys were conducted on January 8, 2006 with the author of this thesis, Dr. Sasowsky (supervisor of the thesis), and Dan Check (a colleague graduate student) as members on the surveying team.
17
2.2.2.1 Survey of Cave Passage
A general map of Scott Hollow Cave existed. However, a detailed map of the
Chris’ Trunk passage was needed for this study. To create this, a total of 16 survey stations (CTS1 – CTS16) were established to cover the entire length of Chris’ Trunk from the upstream end of the lake deposit to the downstream base of the dam which was hypothesized to have created the lake deposit. The horizontal angle between stations was measured using a Suunto compass. This was followed by a corresponding vertical angle measurement using a Suunto clinometer, along with left, right, down and up distances from the survey stations to the cave walls.
The distances between stations as well as the vertical distances of cave walls from the survey stations were measured using a Disto A6 laser device. This was followed by sketching of the station and its surroundings. The above procedure was carried out at all
16 survey stations.
A detailed sketch of the overall area was then made showing the morphology of cave, the breakdown blocks, stream cuts, and the location of the lake deposits relative to the blocks and stream. Upon return to the office, the survey data were processed using the software Compass (Fountain Software, 2007), and a final map and cross-section of the area were made using this output.
2.2.2.2 Survey of Sediment Deposit
The lake sediment deposit was surveyed by establishing 6 survey stations at 5 meter intervals with labeling as 0 m station, 5 m station, …., 30 m station along the entire reach of deposit. These stations began at cave survey station CTS 1, and continued in the
18 upstream direction to the last of the 6 stations. At each station, distances such as the entire width of passage across the room, vertical thickness and lateral width of deposit to the stream, as well as the top of deposit to the ceiling of cave, were measured with the
Disto A6 device. Sketches were made of the morphology of the deposit at the established station with respect to the stream flow pattern, and distances measured from ceiling, cave walls, and stream location.
Also, at select survey stations, sediment thicknesses were determined by pushing a tile probe of length 208 cm and diameter 1.2 cm into the floor until bedrock was intercepted and penetration was halted. The probe was then pulled out and the length of probe that penetrated sediment was measured with a metric fiberglass tape. Figures showing the crossections constructed are given as part of the results under section 3.2.4
(see Plate 2).
2.2.3 Descriptive Stratigraphy and Sampling of Lake Deposit
Continuous sediments that appeared to have been deposited in the conduit during the same time frame or period were sampled. Five profiles were sampled from 5 locations along these deposits; 2 of which were from the northern bank (profiles JNA Section 2 and
JNA Section 3) and 3 from the southern bank (profiles JNA Sections 1A, 1B and 1C).
Along each profile, depositional units that had been identified by boundaries presenting a sharp or gradational contact, and suggesting different depositional regimes, were selected for sampling. Sedimentary structures such as cross-bedding and laminations were noted at each point. This was also accompanied by description of the sediment type, color, dominant grain size fractions, and bedding thickness (Figure 2-4).
19 Key
Layer contacts
JNA 001 – 004 Paleomagnetic Samples
0 8
Centimeters
Figure 2-4. Photograph showing paleomagnetic sampling process.
Also, photographs of features in the conduit were taken. Bedding boundaries reflecting different depositional regimes were marked with a popsicle stick (Figure 2-4).
Duplicate paleomagnetic samples were taken from the natural exposures using a
Brunton compass, oriented plastic sample cubes, resin mallet, paper towels, plastic spades, tape measure and plastic putty knifes. Measurement for sample taking includes the strike, tilt angle, dip and dip direction of the deposit (Sasowsky, et al., 1995). Figure
20 2-5, shows an example of the sampling locations and the demarcation of the different sediment layer contacts within a deposit. The paleomagnetic samples were labeled JNA
001 – 028.
Upper terrace Southern Deposit
JNA JNA
tional Section 1B Section Profile sequence Upper deposi Upper
Boundary
Lower terrace
Figure 2-5. Photograph showing sampling from the upper terrace of southern deposit, profile JNA Section 1B.
Bulk sediment samples for both grain – size analysis and environmental magnetic measurements in the laboratory were taken using plastic bags and a plastic spade from the five different profiles. Figure 2-5 shows how sampling from the JNA Section 1B profile was made. Figure 2-6 shows the respective sampling and profile locations in relation to position of the dam and stream passage in the cave.
21
Figure 2-6. Plan view sketch showing cave, sediment deposit, location of dam, and stream direction.
The labeling scheme used for sediment sample collection includes two parts. The first profile is labeled JNA Section 1A-L1, which represents profile 1A and the first sampled layer as L1 (from the top). The abbreviation “L” signifies layer and the number
“1” signifying the sediment layer being sampled. The color of every sample taken was determined using the Munsell color scheme.
2.3 Laboratory Methods
This section presents methods used to separate each collected sample by clast composition and to compute the percentage compositions of gravel, sand, silt and clay size fractions.
22 2.3.1 Grain Size Analysis
The study of sediment grain sizes is important for a variety of reasons. First and foremost, grain size study is essential in the classification of sedimentary environments
(Blott and Pye 2001). Grain size study is also known to serve as the fundamental descriptive measure of siliciclastic sedimentary rock (Boggs, 2001). The understanding of the mechanisms involved in sediment transportation and the distance that sediment has been transported before getting deposited is important. The reason being that, these mechanisms can influence how the sediment grains are sorted within the deposit. Also a mechanism such as conditions that caused the transportation of the sediments can be inferred from the sorting history through grain size analysis (Forstick and Reid, 1980).
2.3.1.1 Measuring Procedure
In the present study, grain size analysis was done using both the sieving and pipette methods. A summary of the experimental procedures is shown in Figure 2-7.
2.3.1.1.1 Methodology
Representative portions of the bulk samples were taken and dried at room temperature in a fumehood for two weeks to determine the exact sample mass on an electronic balance to 0.001g. A 250 mL sodium metaphosphate solution was added to the sample and the mixture was made up to 500 mL with dionized water (DI). This was then wet – sieved to separate the grain sizes less than 63 μm into the 500 mL beaker with the use of a sieve and de-ionized water (DI - water). The grain sizes greater than 63 μm (sand sizes), were washed into a clean cup and labeled with the sample name and grain size fraction.
23 Bulk samples from field
If sample is sandy clay or If sample has substantial with high % of mud gravel fraction
Wet Sieve with DI at 63 Air dried in fumehood µm
Muddy water ≤ 500 mL of Hand sieve to separate
water at the end of sieve sand from pebble
Grain size analysis with Sand size fraction
24 pipette method (< 2 mm)
XRD analysis Ro-tap to attain detailed sand size fractions
Sand Fractions > 2 mm
Dry sieve for grain size Determine size fractions analysis using constructed sieves
Figure 2-7. Chart showing treatment of samples for grain-size analysis. A pipette analysis was then performed on the separated muddy samples resulting from the wet sieve process following the procedure outlined in Folk (1980). The sandy grain size fractions contained in labeled cups were then air-dried in a fume-hood. The method enumerated above was followed for all the samples to have dried samples ready for the Ro-tap step.
Each dried sandy sample was then Ro-tap sieved at ½ intervals for five minutes to separate the bulk grains into the various grain sizes present (Folk, 1980). The stack of sieves in the Ro-tap machine was then removed, and the contents poured and weighed on a balance to determine the mass of the fractions. Folk (1980) gives a conversion table for phi ( ) values into microns which serves as the basis for the conversion in this analysis.
2.3.1.2 Treatment of Grain – Size Data
The treatment of grain size data is influenced by the purpose of the research for which the analysis is intended. For example, the U.S. Geological Survey (2003) reports that the statistical measures of size distributions used by sedimentologists are most commonly based on quartile measures (Trask, 1932), phi notation (Inman, 1952; Folk &
Ward, 1957), or the methods of moments (Kane & Hubert, 1962; Folk, 1974; Sawyer,
1977).
Three mathematical measures of average grain size are in common use. These mathematical measures are the mode, median and sorting (Boggs, 2001). These grain-size statistical parameters can mathematically be calculated using the method of moment without making reference to graphical plots, given formulae for the computations as follows (Boggs, 2001);
25 fm Mean, = x n
2 f (m x ) Standard Deviation, 100
3 f (m x ) Skewness, Sk 3 100
4 f (m x ) Kurtosis, k 4 100
where, f = weight percent (frequency) in each grain size grade present.
m = midpoint of each grain – size grade in phi value.
n = 100 if the values of f are computed in percent
2.3.2 X-Ray Diffraction (XRD)
Bulk sample and clay separate mineralogy measurements were performed on both cave and sinkhole samples. The detailed procedures are outlined in the sections below.
2.3.2.1 Bulk Sample Mineralogy
20 grams of the sample whose bulk mineralogy was to be determined was measured into a labeled plastic cup and placed in a fume hood to be air dried. The air dried sample was pulverized into powder using a Spex powder mill. A powder pack was then made from the sample for X-ray analysis. Samples were scanned using a Phillips X- ray unit (XRG 3100 X-ray generator) running at 40 kV and 35 mA of nickel-filtered copper anode tube. A 2θ limit of 35º was used because no useful information came from
26 longer pilot scans. This procedure was followed in the determination of the sample mineralogy for all collected samples.
2.3.2.2 Clay Mineralogy
About 5g of sample was placed into a 50 mL plastic test tube. Dionized water was then added to the sample to make up to about 75% of the volume. The tube was capped and shaken to enhance disaggregation of the sample. It was then sonicated to further break and release the clay particles contained in the sample into suspension. A portion of the sonicated sample was poured into a test tube to about 2/3 (33 mL) full and centrifuged at 2000 revolutions per second for 1 minute 30 seconds.
The liquid suspension produced was removed and the density determined using the optical clay suspension densitometer. Using a designed calibration curve (Foos and
Quick, 1988), the volume of suspension to be filtered was determined and pipetted using a 10 mL graduated pipette tube. The pipetted volume was poured into a vacuum apparatus which houses a 0.45 μm pore size, 25 mm diameter cellulose nitrate membrane filter supported in a funnel. The apparatus was turn on and allowed to drain under vacuum. The moist clay sample left on the membrane filter was transferred onto a dried glass slide and allowed to dry for 24 hours before X-ray diffraction analysis using the
Phillips X-ray unit (XRG 3100 X-ray generator).
In the diffraction process, the air dried samples were first X-rayed. The samples were then glycolated using the cold vapor method. The oriented clay samples were placed in a desiccator with ethylene glycol at the bottom and then allowed to stand for 24 hours to expand the clays. The samples were then removed and X-rayed again. Afterwards, the samples were heated in a furnace at a relatively low temperature, (400º Celsius) for about
27 30 minutes and then re-analyzed. This step was followed by heating the samples at a higher temperature (550º Celsius), also for 30 minutes. The samples were allowed to cool and then subjected to final analysis.
2.3.3 Magnetic Parameters of Sediment Samples
Portions of the acquired samples were air dried in the fumehood to eliminate moisture content. A 5.28 cm3 plastic box was then packed tight with the air dried samples for environmental magnetism measurements after large clasts size fractions had been removed. Magnetic susceptibility and frequency dependence were measured using a
Bartington MS2 magnetic susceptibility meter. This was followed with an Anhysteretic
Remanence Magnetization (ARM) measurement and demagnetization of the ARM moments imparted using an ASC Scientific D – 2000 A. F. Demagnetizer and a Molspin
Minispin Spinner Magnetometer. These same samples were then magnetized in a direct current field till they attained saturation. The Saturated Isothermal Remanent
Magnetization (SIRM) they acquired was then measured and demagnetized using an ASC
Scientific IM-10-30 Impulse Magnetizer and a Molspin Minispin Spinner Magnetometer.
Figure 2-8 gives a summary of the magnetic measurements made on both sinkhole and cave sediment samples. Ratios from the susceptibility, ARM and Isothermal
Remanent Magnetization (IRM) values measured were computed so that inference could be made with regards to the dominant magnetic mineral grain size present in each analyzed sample, as well as the magnetic mineral concentration and the mineral types present. Also the contributions of organic matter present on soil samples from the sinkhole were determined using the approach by Dean (1974).
28
.
Magnetization (ARM)
Anhysteretic Remanence SIRM demagnetization
IRM (SIRM)
IRM acquisition to Saturated Magnetization (IRM) Isothermal Remanence
moment ARM ARM imparted magnetization of magnetization ARM De
susceptibility Frequency dependence of
Magnetic Susceptibility
Flowchart showing treatment of samples for environmental magnetic measurement environmental magnetic samples for showing treatment of Flowchart measurements
.
Environmental magnetism
8
e
- plastic 3 box box tight fragments each sampleach Samples Samples Figure 2 Figure Air dry about 20 g of 5.28Pack cm Pulverized to remove coarse
29 CHAPTER III
RESULTS
3.1 Sinkhole
This section gives the findings on the magnetic, X-ray diffraction and lithology analyses made on the two soil profiles SH-Soil-1 and SH-Soil-2 from the sinkhole closest to the upstream termination of Chris’ Trunk. Color description followed the Munsell color scheme.
3.1.1 Lithology and Mineralogy on Soil Profile SH-Soil-1
The first profile in the sinkhole was SH-Soil-1. The total excavated thickness was about 173 cm and comprises 9 different soil layers (Figure 3-1). The topmost unit, 8 cm thick, was composed mainly of roots and grayish in color. This layer was not sampled.
Layer 1 (L1) was a 35 cm thick very pale brown gravelly silt, and very poorly sorted
(Figure 3-2). L1 contains 63% silt with about 12% gravel size fraction. The gravel is sub- rounded to subangular shale fragments. X-ray diffraction analysis on the bulk and