Post by Sharon Faulkner on Apr 30, 2006 19:45:38 GMT -5
Abstracts from presentations made during the Geology Session at the 2005 NSS Convention:
Why do TAG caves look the way they do? This symposium brought together a dozen specialists in TAG caving to discuss the way in which geology, groundwater, and topography have controlled these distinctive cave patterns.
The objective of this research is to investigate the hydrogeology of Lookout Mountain, Tennessee, funded by the National Park Service to better understand karst groundwater under its 12 km2 park and the possible effect of nearby urban development on karst and groundwater quality. Major karst flow routes under Lookout Mountain have been identified, and the drainage basins for the major cave streams and springs have been delineated. If a major spill of toxic material were to occur on Lookout Mountain, as happened in 1996, the NPS must be able to track the contaminant movement. Lookout Mountain is a synclinal mountain in the folded Appalachians with the same stratigraphy as the Cumberland Plateau. Caves are mainly oriented along the strike, with vertical shafts where cave streams drop through resistant strata. Dye tracing and cave exploration and mapping were used to investigate the hydrogeology. A hydrologic inventory was conducted on and around the base of Lookout Mountain, and charcoal dye receptors were placed at all springs and streams, and at several locations inside caves. Four different dyes were simultaneously injected into karst sinks on three separate occasions. The results show that cave streams are trapped by the synclinal structure of Lookout Mountain and flow along the strike. Cave streams have a stair-step pattern as they beach perching layers and descend through the Pennington, Bangor, and Monteagle Limestones. The deepest vertical shaft, Mystery Falls (85.6 m) was formed as a cave stream dropped off the perching Hartselle Formation into the Monteagle.
Tumbling Rock Cave is a valley-wall conduit that has developed along the Cumberland Plateau Escarpment of northeast Alabama. Recent dye tracing confirms that the cave functions as a drain for Round Cove, a closed depression at the head of Mud Creek Valley. However, only a small percentage of the injected dye was recovered, which suggests that the cave and surrounding area are hydrologically more complex than originally thought. The main stream passage in Tumbling Rock trends subparallel to and within the eastern wall of the Mud Creek Valley, which suggests that flow paths were guided by stress-relief fracturing. The cave contains multiple levels of passage development. Some of those levels are associated with the allogenic paleo and modern stream within the cave. Higher passage levels, including the Topless Dome, which reaches 120 m in height, are associated with an epikarst aquifer.
While the Mammoth area is famous for being ruled by river-controlled phreatic tube levels, many parts of the cave are heavily controlled by the path that vadose water takes from its point of entry to some far-off base level destination. A big factor affecting these pathways is the presence of perching layers, which may be chert or dolomite. Vadose water flowing on these perching layers results in the formation of vadose tubes, or vadose passages which have a surprisingly significant tube aspect to their shapes. Vadose tubes can be many thousands of feet long, and form an important backbone of the connected cave system. Many passages that are considered to be "base level" are well above the true regional base level, and owe their continuity to perching layers. A poster-child example of a vadose tube is Canis Minor and Canis Major in Sides Cave. These passages, which start as two branches and then merge into one, originally took water from Cooper Spring Hollow on a horizontal journey of approximately 900 m, finally dumping into a dome at its far east end. The passage later experienced up to six successive piracies, working gradually west toward its origin. Vadose tubes make us look at exploration prospects differently: (1) Upstream is as good as downstream. (2) Leads at the tops of domes are often very promising. (3) Major passages can exist independently at each level, with little interaction between levels. The same principles apply to many caves throughout the Southeast.
Surface streams flowing off the sandstone caprock of the Cumberland Plateau onto the underlying carbonates tend to invade the subsurface, creating caves that take a stair-step route to resurge as springs at the escarpment's base. Surface streams usually sink upon flowing onto the Bangor Limestone. They then tend to drop down vertical shafts until they hit the Hartselle Formation, which is primarily sandstone and shale. Bangor cave streams often resurge along the Hartselle Bench about half way down the escarpment and drop as spectacular waterfalls into large sinkholes in the underlying Monteagle Limestone. The cave streams then tend to take a stair-step route down through the Monteagle and St. Louis Limestones to finally resurge in the upper Warsaw Formation near the escarpment base. Many cave streams in the Bangor breach the Hartselle Formation behind the escarpment along stress-relief fractures, thus creating the deep vertical shafts and spectacular underground waterfalls for which TAG caves are noted. In places, even relatively large rivers (such as the Caney Fork and Cane Creek) sink into the Monteagle and St. Louis Limestones, creating large caves (such as Camps Gulf Cave) and then resurge further downstream. Also, large karst valleys (such as Grassy Cove) have formed where surface streams have breached the sandstone caprock, often along structural highs, several kilometers from the edge of the escarpment. As the sandstone caprock is removed by slope retreat, it leaves behind a sinkhole plain that follows the retreating escarpment.
Redstone Arsenal covers 154 km2 in Huntsville, Alabama and contains 424 identified springs, 1886 mapped sinkholes, a highly evolved epikarst, solution cavities in ~70% of bedrock boreholes, and 26 mapped caves. It is situated on the south flank of the Nashville Dome where geologic structure is usually assumed to consist of gently southward dipping beds of Mississippian-age carbonates overlying the Chattanooga Shale. Five distinct hydrogeologic regimes have been identified, and a generalized network of subsurface conduits is inferred from a structural-stratigraphic model. Recently the Army completed nearly 50 km of reflection seismic surveys, nine dye traces, and 32 deep coreholes, documenting significantly more complex structure than previously imagined, with block faulting superimposed on the regional dip. Faulting apparently played a significant role in development of shallow karst aquifers, as shown by dye tracing, and may also have facilitated deep karst development. Drilling revealed transmissive solutional voids up 6 cm thick below the Tennessee River baselevel in the lower Tuscumbia limestone and Fort Payne formations. These strata host natural hydrocarbons that are probably related to block faulting. Groundwater in deep strata are rich in Na-SO4, grading into Na-Cl water downward toward the Chattanooga Shale. Pyrite and gypsum infilling in deep cores, H2S and methane at depth, and the distinct water chemistries may suggest a hypogenic origin for the deep karst development. The faulting may be responsible for the juxtaposition of all of these conditions, and for the karst and caves as well.
Caves are numerous along the Highland Rim Section of the Cumberland Plateau Province, but they are not exceptionally long, despite propitious lithology. The majority of caves form along the escarpment front where streams flow off the protective caprock onto limestone, to emerge close by at the escarpment foot. Such caves tend to be abandoned and destroyed as the escarpment retreats. In a few cases, caves have developed in inliers of limestone. The associated closed depressions become fragmented as they develop, although a substantial trunk conduit may persist beneath a protective caprock. The longest caves in the region tend to parallel valley sides, and there has been some debate concerning the origin of such "Cumberland" type caves. The landscape in northeastern Alabama has been disrupted by cycles of river incision and aggradation, and by epochs of delivery of excessive sediment loads from the escarpment. River incision leads to stimulation of cave development, abandonment of high level routes and development of links concordant with lowered base level. Subsequent rise in base level has caused burial of sinks and springs and obstructed deeper passages. Clastic sediments have choked sinkholes and redirected surface streams. Large alluvial fans formed in valley heads, probably several million years ago. These fans have redirected surface drainage and appear to have stimulated development of Cumberland type caves along their margins.
The Cumberland Plateau in central Tennessee and northern Alabama is blessed with a rich population of caves of many lengths, passage sizes and origins. The calculations described here address the large-cross-section trunk passages that form either active or paleo master drains. The coves of the Cumberland Plateau are incised into the sandstone-capped upland. High-gradient streams descend the walls of the coves often by underground routes with much vertical development. Valley bottoms also provide the gradient for even lower gradient master trunk development. The volume of trunks represents the tradeoff between rate of conduit development and time of stable base level. Cosmogenic isotope dating of sediment in master trunks by Anthony and Granger has provided a time scale into which cave development must be fitted. With chemical data on active drainage systems as a reference, combined with models for rates of passage development, the calculated time scale for development of master trunk drains is in the range of 10,000-50,000 years. Rapid development of master drains with low hydraulic resistance results in underdraining of valleys. Calculated development times are shorter by an order of magnitude than periods of stable base level indicated by the Anthony and Granger dates. Reconciliation of these data requires a damping effect on cave development probably due to sediment infilling and by the development of protective barrier layers on cave walls. Evidence for the latter is provided by the observed transmission of low-pH acid mine water.
TAG (Tennessee, Alabama and Georgia) is home to a significant number of vertical caves. In this region, caves that have a vertical extent of a hundred meters or more are considered "deep." Approximately 1% of all TAG caves fall into this category. Many deep caves are characterized by shafts that are separated by long crawlways and short stretches of borehole before reaching base level. Other deep caves consist of multiple shaft routes to base level. Some deep caves have significant lateral as well as vertical extent that reflect major changes in base level over time. And some deep caves attain their vertical extent from epikarst domes that have fortuitously intersected paleo trunk passages. The morphology, lateral extent and vertical extent of deep TAG caves are a function of stratigraphic, structural, hydrologic and geomorphic controls. These controls vary across the physiographic provinces that typify the TAG region and between the two major watersheds that drain it.
To link to or bookmark this page, use the following url: www.google.com/search?q=cache:fDDl_UXRFwgJ:www.nss2005.com/tag.htm+TAG+caves+&hl=en&lr=&strip=1
Geology of TAG Caves Abstracts
Why do TAG caves look the way they do? This symposium brought together a dozen specialists in TAG caving to discuss the way in which geology, groundwater, and topography have controlled these distinctive cave patterns.
Karst Hydrogeology of Lookout Mountain, a Synclinal Mountain in the Folded Appalachian Mountains of South-Central Tennessee
Brian Sakofsky, Kent Ballew, and Nicholas Crawford
Center for Cave and Karst Studies
Applied Research and Technology
Program of Distinction
Department of Geography and Geology
Western Kentucky University
Bowling Green, KY 42101
Center for Cave and Karst Studies
Applied Research and Technology
Program of Distinction
Department of Geography and Geology
Western Kentucky University
Bowling Green, KY 42101
The objective of this research is to investigate the hydrogeology of Lookout Mountain, Tennessee, funded by the National Park Service to better understand karst groundwater under its 12 km2 park and the possible effect of nearby urban development on karst and groundwater quality. Major karst flow routes under Lookout Mountain have been identified, and the drainage basins for the major cave streams and springs have been delineated. If a major spill of toxic material were to occur on Lookout Mountain, as happened in 1996, the NPS must be able to track the contaminant movement. Lookout Mountain is a synclinal mountain in the folded Appalachians with the same stratigraphy as the Cumberland Plateau. Caves are mainly oriented along the strike, with vertical shafts where cave streams drop through resistant strata. Dye tracing and cave exploration and mapping were used to investigate the hydrogeology. A hydrologic inventory was conducted on and around the base of Lookout Mountain, and charcoal dye receptors were placed at all springs and streams, and at several locations inside caves. Four different dyes were simultaneously injected into karst sinks on three separate occasions. The results show that cave streams are trapped by the synclinal structure of Lookout Mountain and flow along the strike. Cave streams have a stair-step pattern as they beach perching layers and descend through the Pennington, Bangor, and Monteagle Limestones. The deepest vertical shaft, Mystery Falls (85.6 m) was formed as a cave stream dropped off the perching Hartselle Formation into the Monteagle.
Geology and Hydrogeology of Tumbling Rock Cave, Jackson County, Alabama
Bill Varnedoe
5000 Ketova Way, Huntsville, AL 35803
Pat Kambesis
Hoffman Environmental Research Institute
WesternKentucky University
Bowling Green, KY 42101
5000 Ketova Way, Huntsville, AL 35803
Pat Kambesis
Hoffman Environmental Research Institute
WesternKentucky University
Bowling Green, KY 42101
Tumbling Rock Cave is a valley-wall conduit that has developed along the Cumberland Plateau Escarpment of northeast Alabama. Recent dye tracing confirms that the cave functions as a drain for Round Cove, a closed depression at the head of Mud Creek Valley. However, only a small percentage of the injected dye was recovered, which suggests that the cave and surrounding area are hydrologically more complex than originally thought. The main stream passage in Tumbling Rock trends subparallel to and within the eastern wall of the Mud Creek Valley, which suggests that flow paths were guided by stress-relief fracturing. The cave contains multiple levels of passage development. Some of those levels are associated with the allogenic paleo and modern stream within the cave. Higher passage levels, including the Topless Dome, which reaches 120 m in height, are associated with an epikarst aquifer.
Perching Layers, Vadose Tubes, and Exploration in Mammoth Cave, Kentucky
James Wells, 120 Gouge Hollow Road
Oliver Springs, TN 37840
Jim Borden 2032 NE Katsura Street,
Issaquah, WA 98029
Oliver Springs, TN 37840
Jim Borden 2032 NE Katsura Street,
Issaquah, WA 98029
While the Mammoth area is famous for being ruled by river-controlled phreatic tube levels, many parts of the cave are heavily controlled by the path that vadose water takes from its point of entry to some far-off base level destination. A big factor affecting these pathways is the presence of perching layers, which may be chert or dolomite. Vadose water flowing on these perching layers results in the formation of vadose tubes, or vadose passages which have a surprisingly significant tube aspect to their shapes. Vadose tubes can be many thousands of feet long, and form an important backbone of the connected cave system. Many passages that are considered to be "base level" are well above the true regional base level, and owe their continuity to perching layers. A poster-child example of a vadose tube is Canis Minor and Canis Major in Sides Cave. These passages, which start as two branches and then merge into one, originally took water from Cooper Spring Hollow on a horizontal journey of approximately 900 m, finally dumping into a dome at its far east end. The passage later experienced up to six successive piracies, working gradually west toward its origin. Vadose tubes make us look at exploration prospects differently: (1) Upstream is as good as downstream. (2) Leads at the tops of domes are often very promising. (3) Major passages can exist independently at each level, with little interaction between levels. The same principles apply to many caves throughout the Southeast.
An Overview of Karst Development along the Cumberland Plateau Escarpment of Tennessee, Alabama, and Georgia
Nicholas C. Crawford, Ph.D.
Center for Cave and Karst Studies
Applied Research and Technology Program of Distinction
Western Kentucky University
Bowling Green, KY 42101
Center for Cave and Karst Studies
Applied Research and Technology Program of Distinction
Western Kentucky University
Bowling Green, KY 42101
Surface streams flowing off the sandstone caprock of the Cumberland Plateau onto the underlying carbonates tend to invade the subsurface, creating caves that take a stair-step route to resurge as springs at the escarpment's base. Surface streams usually sink upon flowing onto the Bangor Limestone. They then tend to drop down vertical shafts until they hit the Hartselle Formation, which is primarily sandstone and shale. Bangor cave streams often resurge along the Hartselle Bench about half way down the escarpment and drop as spectacular waterfalls into large sinkholes in the underlying Monteagle Limestone. The cave streams then tend to take a stair-step route down through the Monteagle and St. Louis Limestones to finally resurge in the upper Warsaw Formation near the escarpment base. Many cave streams in the Bangor breach the Hartselle Formation behind the escarpment along stress-relief fractures, thus creating the deep vertical shafts and spectacular underground waterfalls for which TAG caves are noted. In places, even relatively large rivers (such as the Caney Fork and Cane Creek) sink into the Monteagle and St. Louis Limestones, creating large caves (such as Camps Gulf Cave) and then resurge further downstream. Also, large karst valleys (such as Grassy Cove) have formed where surface streams have breached the sandstone caprock, often along structural highs, several kilometers from the edge of the escarpment. As the sandstone caprock is removed by slope retreat, it leaves behind a sinkhole plain that follows the retreating escarpment.
Structural Controls on Karst Development and Groundwater Flow, Redstone Arsenal, Huntsville, Alabama
Tom Zondlo, Sr. Hydrogeologist
Shaw Environmental & Infrastructure
Knoxville, TN
Shaw Environmental & Infrastructure
Knoxville, TN
Redstone Arsenal covers 154 km2 in Huntsville, Alabama and contains 424 identified springs, 1886 mapped sinkholes, a highly evolved epikarst, solution cavities in ~70% of bedrock boreholes, and 26 mapped caves. It is situated on the south flank of the Nashville Dome where geologic structure is usually assumed to consist of gently southward dipping beds of Mississippian-age carbonates overlying the Chattanooga Shale. Five distinct hydrogeologic regimes have been identified, and a generalized network of subsurface conduits is inferred from a structural-stratigraphic model. Recently the Army completed nearly 50 km of reflection seismic surveys, nine dye traces, and 32 deep coreholes, documenting significantly more complex structure than previously imagined, with block faulting superimposed on the regional dip. Faulting apparently played a significant role in development of shallow karst aquifers, as shown by dye tracing, and may also have facilitated deep karst development. Drilling revealed transmissive solutional voids up 6 cm thick below the Tennessee River baselevel in the lower Tuscumbia limestone and Fort Payne formations. These strata host natural hydrocarbons that are probably related to block faulting. Groundwater in deep strata are rich in Na-SO4, grading into Na-Cl water downward toward the Chattanooga Shale. Pyrite and gypsum infilling in deep cores, H2S and methane at depth, and the distinct water chemistries may suggest a hypogenic origin for the deep karst development. The faulting may be responsible for the juxtaposition of all of these conditions, and for the karst and caves as well.
Speleogenesis in the Highland Rim of Northeastern Alabama
Chris Smart
Department of Geography
University of Western Ontario
London, Ontario, N6A 5C2, Canada
Warren Campbell
School of Engineering
Western Kentucky University
Bowling Green, KY 42101
Department of Geography
University of Western Ontario
London, Ontario, N6A 5C2, Canada
Warren Campbell
School of Engineering
Western Kentucky University
Bowling Green, KY 42101
Caves are numerous along the Highland Rim Section of the Cumberland Plateau Province, but they are not exceptionally long, despite propitious lithology. The majority of caves form along the escarpment front where streams flow off the protective caprock onto limestone, to emerge close by at the escarpment foot. Such caves tend to be abandoned and destroyed as the escarpment retreats. In a few cases, caves have developed in inliers of limestone. The associated closed depressions become fragmented as they develop, although a substantial trunk conduit may persist beneath a protective caprock. The longest caves in the region tend to parallel valley sides, and there has been some debate concerning the origin of such "Cumberland" type caves. The landscape in northeastern Alabama has been disrupted by cycles of river incision and aggradation, and by epochs of delivery of excessive sediment loads from the escarpment. River incision leads to stimulation of cave development, abandonment of high level routes and development of links concordant with lowered base level. Subsequent rise in base level has caused burial of sinks and springs and obstructed deeper passages. Clastic sediments have choked sinkholes and redirected surface streams. Large alluvial fans formed in valley heads, probably several million years ago. These fans have redirected surface drainage and appear to have stimulated development of Cumberland type caves along their margins.
Stable Base Levels, Valley Underdrains, Catchment Areas, and Time: The Interplay Responsible for the Master Trunk Caves of the
Cumberland Plateau
Cumberland Plateau
William B. White
Materials Research Institute and Department of Geosciences
The Pennsylvania State University
University Park, PA 16802
Materials Research Institute and Department of Geosciences
The Pennsylvania State University
University Park, PA 16802
The Cumberland Plateau in central Tennessee and northern Alabama is blessed with a rich population of caves of many lengths, passage sizes and origins. The calculations described here address the large-cross-section trunk passages that form either active or paleo master drains. The coves of the Cumberland Plateau are incised into the sandstone-capped upland. High-gradient streams descend the walls of the coves often by underground routes with much vertical development. Valley bottoms also provide the gradient for even lower gradient master trunk development. The volume of trunks represents the tradeoff between rate of conduit development and time of stable base level. Cosmogenic isotope dating of sediment in master trunks by Anthony and Granger has provided a time scale into which cave development must be fitted. With chemical data on active drainage systems as a reference, combined with models for rates of passage development, the calculated time scale for development of master trunk drains is in the range of 10,000-50,000 years. Rapid development of master drains with low hydraulic resistance results in underdraining of valleys. Calculated development times are shorter by an order of magnitude than periods of stable base level indicated by the Anthony and Granger dates. Reconciliation of these data requires a damping effect on cave development probably due to sediment infilling and by the development of protective barrier layers on cave walls. Evidence for the latter is provided by the observed transmission of low-pH acid mine water.
Geologic Controls on the "Deep" Caves of TAG
Pat Kambesis
Hoffman Environmental Research Institute
Western Kentucky University
Bowling Green, KY 42101
Alan Cressler
US Geological Survey, Atlanta, GA
Hoffman Environmental Research Institute
Western Kentucky University
Bowling Green, KY 42101
Alan Cressler
US Geological Survey, Atlanta, GA
TAG (Tennessee, Alabama and Georgia) is home to a significant number of vertical caves. In this region, caves that have a vertical extent of a hundred meters or more are considered "deep." Approximately 1% of all TAG caves fall into this category. Many deep caves are characterized by shafts that are separated by long crawlways and short stretches of borehole before reaching base level. Other deep caves consist of multiple shaft routes to base level. Some deep caves have significant lateral as well as vertical extent that reflect major changes in base level over time. And some deep caves attain their vertical extent from epikarst domes that have fortuitously intersected paleo trunk passages. The morphology, lateral extent and vertical extent of deep TAG caves are a function of stratigraphic, structural, hydrologic and geomorphic controls. These controls vary across the physiographic provinces that typify the TAG region and between the two major watersheds that drain it.
To link to or bookmark this page, use the following url: www.google.com/search?q=cache:fDDl_UXRFwgJ:www.nss2005.com/tag.htm+TAG+caves+&hl=en&lr=&strip=1
