AN INTRODUCTION TO CAVES AND CAVE EXPLORING IN GEORGIA by Barry F. Beck, Ph.D. Department of Earth Science Georgia Southwestern College Americus, Georgia DEPARTMENT OF NATURAL RESOURCES Joe D. Tanner, Commissioner ENVIRONMENTAL PROTECTION DIVISION J. Leonard Ledbetter, Director GEORGIA GEOLOGIC SURVEY William H. McLemore, State Geologist Atlanta 1980 Table of Contents page Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Types of Caves............................................... 2 Solution Caves in Limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Caves and Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Land Collapse in Karst Terrains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Speleothems-Mineral Deposits in Caves ........................ 12 Cave Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Cave Exploring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 National Speleological Society. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 National Speleological Society Grottos in and near Georgia . . . . . . . . 35 The Cave Protection Act of 1977 ..... ~ . . . . . . . . . . . . . . . . . . . . . . . . . 36 Caves on Private Property or State or Federal Land . . . . . . . . . . . . . . 36 Commercial Caves in the Georgia Area . . . . . . . . . . . . . . . . . . . . . . . . . 39 Supplementary Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 General Books on Caves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 How-To Books on Cave Exploring .............................. 42 Books on Speleology, the Science of Caves . . . . . . . . . . . . . . . . . . . . . . 43 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 iii List of Illustrations page Figure 1. Glacier cave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Cross-section of water in limestone. . . . . . . . . . . . . . . . . . . 4 3. Karst topography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Map of limestone areas in Georgia . . . . . . . . . . . . . . . . . . . 6 5. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6. Diagram of ceiling stoping . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. Sequential diagram of collapse in S. Georgia. . . . . . . . . . . 13 8. How soda straws grow ............................. 14 9. Soda straws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 10. Soda straws in joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11. Stalactites, stalagmites, and columns . . . . . . . . . . . . . . . . . 16 12. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 13. Common speleothems .............................. 18 14. Curtains and bacon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 15. Rimstone dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 16. Helictites and heligmites . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 17. Cave pearls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 18. Gypsum flower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 19. Trogloxene salamanders . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 20. Troglobitic crawfish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 21. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 22. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 23. Cave cricket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 24. Troglobitic salamander.............................. 28 25. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 26. Rock climbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 27. Chimneying ....................................... 31 28. Climbing on rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 29. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 30. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 31. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 32. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 33. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 34. Cartoon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 iv Introduction This booklet was written to help answer some questions about caves and cave exploring, or caving as it is more commonly known. (In the author's experience the term "spelunking" is rarely used by cave explorers, who generally call themselves cavers.) This booklet was also written to explain why caves and their contents are unusual or even unique, how they may be easily damaged, and why they should be protected and conserved. In passing the Cave Protection Act of 1977, the Georgia Legislature and the Governor unanimously endorsed the following proposition. "The State of Georgia hereby finds that caves are uncommon geologic phenomena, and that the minerals deposited therein may be rare and occur in unique forms of great beauty which are irreplaceable if destroyed. It is also found that the wildlife which evolved to live in caves are unusual and of limited numbers, and many are rare and endangered species, and that caves are a natural conduit for groundwater flow and are highly subject to water pollution, which has far-reaching effects transcending man's property boundaries. It is therefore declared to be the policy of this State and the intent of this Act to protect these unique natural resouces." Caves are delicate, and so are cavers. Caving, if approached properly and cautiously, is no more dangerous than any other physical, out-door hobby. Most newsworthy caving accidents occur to inexperienced, ill-informed, and improperly equipped novices who usually have violated one or several basic rules of safe caving. Reading this booklet cannot teach anyone to be a cave explorer; caving techniques can only be properly learned directly from experienced cavers. Finally, if you think this booklet will tell you where to find caves to explore, put it down. Because caves are delicate and unusual natural phenomena, and because most cave accidents happen to poorly prepared beginners, it is the policy of organized cave explorers (members of the National Speleological Society) to restrict information on cave locations. Just as trout fishermen may jealously guard the locations of their secret backwoods fishing holes, cavers guard the locations of their caves. Besides protecting these spots from overuse, litter and vandalism, cave explorers believe they also are protecting inexperienced cavers. By taking beginners on their caving trips and teaching them their techniques and philosophy of caving, they hope to protect our caves for future generations to wonder at and wander in. 1 Types of Caves What is a cave? The answers vary, but almost all agree on several points. It is a naturally occurring opening (occasionally without an entrance); it is larger than a person; and it extends into total darkness. Are all caves formed in the same kind of rock and by the same processes? The answer is yes and no. The vast majority of caves are the same-solution caves formed in limestone. Since most of this booklet is devoted to this type of cave, let us first briefly examine some less common, but equally fascinating, types of caves. The second most common type of cave is the lava cave or lava tube. Lava tubes are formed when a tongue of molten lava flowing downhill cools off and solidifies on the outside. The interior of the flow, insulated and kept warm by the surrounding lava, remains molten and continues to flow downslope, leaving the solidified outer crust as a hollow shell-a lava tube. Lava tubes are generally simple as viewed from above, although they occasionally branch or merge and frequently have multiple levels. Some lava tubes may be more than 10 miles long. The entrances to lava tubes usually are formed by later erosion and collapse of the roof material, although some of this may occur while the lava is cooling. There are no lava tubes in Georgia or the southeastern United States, but they are abundant in the northwestern United States, especially in Idaho, Oregon, and Washington. Idaho's Craters of the Moon National Park is particularly well known for lava caves; others are noted in Hawaii, Iceland, and the Canary Islands. The term glacier caves refers to caves formed in ice (fig. 1) in contrast to caves containing ice, ice caves. (Another term for ice cave is "glaciere," but since this is easily confused with glacier cave, ice cave is preferable.) Glacier caves usually are formed along the course of streams flowing beneath the ice. The stream passage acts as a conduit for air circulation which promotes melting and sublimation (the direct change of ice to water vapor). These ablation (glacier-wasting) processes keep the cave open and enlarge it. Eddies in the air currents vary the rate of ablation locally, and produce the curious pocketed or fluted character common to the walls of such caves. Perhaps the best-known glacier caves in the United States are the misnamed Paradise Ice Caves formed in the glaciers on the slopes of Mt. Ranier, Wash. More appropriately, these should be called the Paradise Glacier Caves. Sea caves are another type of cave. They are undercut areas at the base of coastal cliffs where pounding waves and the rock pieces they carry have eroded notches in the rock face. Frequently, they are localized by weaker layers or cracks in the rock which help initiate the erosion. Sea caves are generally shallow, rarely extending into total darkness. The Georgia coast is not marked by cliffs of durable rock which might be undercut, and therefore has not developed any sea caves. In the United States, sea caves are best developed on the Pacific coast of Washington, Oregon, and northern California. Anemone Cave in Acadia National Park, Maine, is also a sea cave. 2 Figure 1. A glacier cave in Washington showing the typical scalloped walls . Photo courtesy of Dr. William R. Halliday . Yet another variety of cave may be classed as tectonic caues. These are caves formed by the cracking and movement of rock layers, leaving open spaces. Somewhat similar are boulder or talus caues-openings between boulders piled up at the base of a cliff or slope. Occasionally these winding cracks ex tend hundreds of feet beneath extensive piles of debris. Minor caves of this type might be found in middle and northern Georgia . Rock shelters are occasionally known as caves to the local residents. These are undercut areas at the base of cliffs where weaker, less stable layers of rock have been removed by erosion , and massive, durable layers have remained overhead , forming a roof. These areas frequently were shelters for early man and often are archaeological sites. An undercut of this type occurs alo ng the trail which leads down into the canyon at Cloudland Canyon State Park in northwest Georgia. There, crumbly shales have been removed , and a massive sandstone and conglomerate ledge remains to form a roof. This shelter is high enough to stand up in and frequently is a resting point for hikers. 3 Solution Caves in Limestone The vast majority of the caves we see or hear about are solution caves in limestone. These caves are formed by flowing underground water dissolving the rock material (fig. 2). They are only one feature of what geologists know as karst topography, a land surface characterized by bedrock which has been dissolved by chemical weathering rather than worn away by abrasion. Karst surfaces are commonly marked by sinkholes, caves, and an absence of surface streams (fig. 3). Although karst topography may form on any type of soluble rock, it is most extensively and intensively developed on limestone. Limestone is a sedimentary rock made up of particles deposited in layers at the earth's surface (including under the sea).lt may be deposited in several ways, but the particles are always made up of calcium carbonate ( CaC0 3), usually in the form of piled-up shells and skeletal materials from marine organisms such as oysters, corals, and snails. What is now a thriving coral reef in a tropical ocean will one day be a layer of limestone containing coral fossils. Vertical jo1nts enlarged by dncendinQ woteri widened at the top ~ Limutone ~Stream Figure 2. Generalized cross section showing water flow through limestone and the cave-forming process. 4 R"urgenu Sprint Collopse Sinkhole Solution S""holo Blind Valley with Sir*ii'IQ Stream Figure 3. Generalized sketch of some common karst landforms. In the shallow water behind the coral reef, numerous tropical algae build pea-sized plates of calcium carbonate. Debris broken from reefs by pounding waves is mixed with these plates to form a coarse, cream-colored sand. Layers of this sand later become limestone. Calcium carbonate is also dissolved in seawater, like salt. When the sea water evaporates, layers of calcium carbonate are deposited, just like the crust of minerals deposited in the bottom of a pot of water allowed to boil dry. This process may form layers of limestone on tidal flats or beaches subject to daily wetting and drying. These processes of limestone formation are working today in clear tropical waters. Both southern Florida and southern California have excellent coastal environments for depositing limestone. However, these same processes also operated in the past. Thousands and millions of years ago, tropical seas existed in areas where today there are high mountains. True, the shells preserved in these limestones were different from those we find now, but the processes of limestone formation were the same. Limestone is found in several areas of Georgia (fig. 4). The solution of limestone is actually a reaction involving the gas, carbon dioxide (C0 2). Limestone is only sparingly soluble in pure water. However, as carbon dioxide is added to water, a weak acid, carbonic acid, forms. This 5 SIGNIFICANT AREAS OF LIMESTONE OUTCROPS IN GEORGIA NOTE= In Northwestern Geor;o,the limestone may alternate with sandstone and shale. ~ V"/?) Limestone; possibly intlflayered with other rock types I Escarpment (the small lines indicate the low tide) Figure 4. Limestone areas in Georgia. acid helps attack the limestone, and reacts with it to change it into solub), products. The more carbon dioxide there is, the more limestone can b dissolved. We can write this reaction chemically as follows: C02 + H20 carbon dioxide water -+ H2C03 carbonic acid H2C0 3 + CaC03 -+ Ca++ + 2(HC03r carbonic acid limestone calcium bicarbonate ions ions in solution 6 When bare limestone is exposed at the earth's surface, it is subject to the attack of rainwater weakly acidified by the small amount of carbon dioxide in the atmosphere. However, when rainwater percolates through the soil it absorbs more carbon dioxide, which is formed by the decay of plant material. Thus, if the limestone is soil-covered, the acid attack is much more intense. Climate also plays a role in this solution process. Cold water dissolves ~ore carbon dioxide than warm water does. This is easy to visualize when you think of a can of soda. Warm soda fizzes a lot when opened (loses carbon dioxide), but cold soda does not, because it can hold more carbon dioxide in solution. It appears, as it did to some early geologists, that cavern formation would be more intense in cold climates. However, other factors counteract the basic temperature effect. In warm climates considerably more vegetation is present, and it grows all year around. Thus the soil is more carbon-dioxide rich. Also, in tropical climates considerably more precipitation is available to dissolve the limestone. Further, most chemical reactions proceed faster at warmer temperatures. Thus, the combination of all these factors makes the process of limestone solution much more intense in warmer climates. Now that we understand the solution process better, let us look at how flowing water actually hollows out the limestone into caves. When precipitation falls on a porous rock layer, it soaks into the rock (infiltration) and seeps downward under the force of gravity. Most limestone is not porous, but is cut by numerous cracks called joints. Water seeps downward along these joints, eventually reaching a level where all fractures and openings are full of water. The upper limit of this water-filled zone is known as the water table. The water beneath the water table flows laterally and drains from the rock at low points, or springs. It is this lateral flow of ground water which forms caves. When water first seeps into the limestone from the soil, it is very rich in carbon dioxide. It dissolves limestone rapidly, losing most, but not all, of its ability to dissolve. This rapid surface solution creates sinkholes and vertical shafts. However, when the descending water reaches the water table it can still dissolve more limestone. As it moves laterally in a thin zone just below the water table, it enlarges the cracks through which it is flowing. If one crack is somewhat larger, it transmits more water flow. The larger volume of water is capable of dissolving more limestone, so this crack grows faster than the others. As this process perpetuates itself, one crack eventually carries the vast majority of the flow and is enlarged into a cave. The cave, then, is a water conduit. It collects water from one area through sinkholes or cracks in the limestone, and transmits it to another area through a naturally formed plumbing network. Most limestone caves form as a result of this water circulation. Their original hydrologic role frequently is obscured by the breakup of the cave into many isolated segments due to roof collapse, sediment buildup, or massive mineral deposition. Indeed, local valleys may deepen until the cave is left high above ground-water level, and totally dry. Where might such conditions and processes take place in Georgia? Obviously, in areas where limestone exists. The two general areas of limestone outcrop in Georgia-one in the northwest, the other in the southwest-are made up of very different types of limestone (fig. 4). The limestones in northwestern Georgia are very old-about 350 million years old. They are very hard and dense, and water can only move through them along joints. They frequently are exposed on the slopes of long mountain ridges; therefore, water entering the limestones must sink long distances downward before moving laterally. This area of Georgia contains many caves with deep pits, the result of solution by descending water. In fact, the deepest pit in the United States is in northwestern Georgia: 586 ft. deep, about the height of the tallest Atlanta skyscrapers. It is easy to see why cave exploring in this area must be approached with caution. In southwestern Georgia the limestones are distinctly different. They are much younger-only 25 million years old-and they are much more porous. In between the pieces of shell and other grains are voids-pore spaces where water may move. This porosity is unusual for limestone. There also are joints which give the water even easier paths to travel. That area of Georgia extending from the southwest corner of the State through Albany to Dooly County on the northeast, and characterized by a relatively flat land surface, is known as the Dougherty Plain. It is underlain by these limestones. Within the limestones there are sinkholes and cavities. However, because the limestone is relatively flat and close to the level of the Flint River, which drains the area, most of these are water filled. The sinkholes can be seen on aerial photographs and on topographic maps. We know the caves exist here because water wells have intercepted them, and because large perennial springs in limestone, such as Radium Springs, usually are fed by flow from open conduits. The eastern edge of the Dougherty Plain is marked by a long, low ridge variously known as the Curry Ridge or the Pelham Escarpment. This ridge is the edge of the overlying layers of rock, and here some limestone is exposed at slightly higher elevations. Thus, there are a few caves above the water table. It formerly was thought that the cave-forming process was principally responsible for eroding this ridge by dissolving it. However, more recent data on the caves conflicts with this idea. Caves and Water Supply Because caves are an integral part of water circulation in limestone, they obviously are closely related to water supply. In areas of karst terrain, water availability is often problematic. Most surficial water sinks rapidly into the ground along enlarged joints; therefore lakes and rivers are few in extensive karst areas. Beneath the ground the water is confined to a few large, open conduits because most limestones are dense and impermeable like those in northwest Georgia. Thus, surface-water supplies are almost nonexistent, and well-water supplies are a gamble. If a well intercepts a cave, water is bountiful; if it does not, the yield is very little or none. Cave explorers have provided valuable assistance to landowners by accurately mapping a cave so that a well may be drilled at exactly the right spot to intercept the water flow. The limestones in southwest Georgia and Florida are usually porous, and there, most wells have a high yield. In karst areas, ground water (the geologic term for water which has seeped into the ground) is very different from ground water in other areas. Most usable ground water occurs in granular aquifers. An aquifer is a layer of rock 8 yielding usable quantities of water, and a granular aquifer is such a layer made of grains, usually sand and gravel. The water moves slowly through a multitude of minute pores between the grains. It is everywhere. The velocities of ground-water movement in a granular aquifer are about several inches to 10ft/day. Even the faster velocities are an exceedingly slow 0.00008 mi/hr. The slow movement of water through these small pores allows natural biologic and chemical processes to degrade pollutants and to purify the water. The minute pores also serve as sieves, straining out many pollutants. Thus, ground water in granular aquifers is naturally purified. In contrast, ground water in karst areas is easily and rapidly contaminated. Because the water flows through large openings, it is little strained or filtered. For the same reason, it can move more rapidly-tens, hundreds, or even thousands of ft/day. This rapid flow transmits pollutants great distances before natural processes can purify them. Several well-documented instances are recorded in Missouri, a state noted for its caves and karst terrain (Aley, 1974). In one case, dye flushed down the toilet at a Springfield school showed up in a nearby city-park spring. It had travelled about 50 ft/day. In another instance, septic tank drainage near Doniphan, Mo., was traced to a nearby well in less than three days. Bacteriologic sampling of the well indicated the water unsafe for human consumption. Figure 5. It is illegal to dump refuse in caves or sinkholes in Georgia. Cartoon by Charlie Loving. 9 Similar effects can be found in Georgia. Near Valdosta the Withlacoochee River disappears into a sinkhole. Wells in a broad area south-southwest of this point pump the highly colored "black" water, characteristic of south Georgia surface streams. "The recharged, highly colored water migrates rapidly downgradient and is withdrawn from wells before any natural filtering and color removal can occur. The migration from the recharge area is probably facilitated by channels or solution openings..."(Krause, 1976). In the northwestern town of Chickamauga, Crawfish Spring flows in quantities of 9 to 23 million gal/day from solution openings in limestones and dolomites (a rock chemically similar to limestone with magnesium added). However, wells in the Chickamauga area cannot be used for drinking water without expensive treatment, because of high bacterial counts probably originating from local septic tanks and transmitted rapidly through the same large solution conduits. It has long been the policy of the Land Protection Branch of the Environmental Protection Division, Georgia Department of Natural Resources, to prohibit the dumping of wastes in sinkholes for exactly the reasons documented above. The Cave Protection Act of 1977 has solidified this policy into law: "It shall also be unlawful to dump, litter, dispose of or otherwise place any refuse, garbage, dead animals, sewage, trash, or other such similar waste materials in any quantity in any cave or sinkhole." (Sec. 6, Act No. 352 of 1977.) Land Collapse in Karst Terrains Collapse is an integral part of cave development. In many caves the floor is littered or piled high with what cavers call "breakdown" (blocks of collapsed material from the ceiling and walls). This process occurs in response to the constant pull of gravity whenever a portion of the ceiling is no longer able to support its own weight. This frequently happens as a passage grows wider, leaving the roof unsupported. It is particularly common in thin-bedded rocks and less common in more massive, stronger limestones. A common mechanism of upward collapse is called stoping (pronounced with a long "o"). As one layer of rock collapses, it exposes the next layer above it to the inexorable pull of gravity. Eventually, this layer cracks and weakens, exposing the layer above. Of course, the process narrows upward since the edges of each layer are supported by the underlying layer and therefore tend to stay in place (fig. 6). This upward stoping collapse continues until either a strong layer is encountered or the surface is breached. In the latter case, a sudden catastrophic collapse may result. The hole formed is known as a collapse sinkhole in contrast to one formed by solution. Such land-surface collapse, or sudden subsidence, occurs naturally as a part of karst terrain development. However, it frequently is accelerated or triggered by man's activities. One obvious way this happens is by placing additional weight on the roof. This was vividly demonstrated by the City of Fort Gaines sewage treatment lagoon. The pond was located on top of the very porous Clayton Limestone, a relatively thin limestone outcropping in a narrow band 10 in western middle Georgia. When the pond was filled with sewage, the bottom collapsed and the entire lagoon rapidly drained underground.The hole was plugged with concrete and the lagoon refilled. Again it collapsed. Again it was plugged. Eventually the bottom was stabilized, but only after considerable expense and probable ground-water contamination. A frequent triggering mechanism for land-surface collapse in karst areas is a sudden change in underground water levels. Water exerts a buoyant, floating effect on the rocks immersed in it. Thus, part of the weight of a cave roof may be supported by this buoyancy. If the water level is lowered, either by pumping or by a drought, this support is removed. The roof may no longer be able to support its own weight and may suddenly collapse. ceiling formed by upward stopint cellopse walls formed by solution Figure 6. Cross section showing upward stoping of a cave ceiling. 11 Land-surface collapse does not necessarily have to be caused by the presence of a gigantic cave, however. In southwestern Georgia the limestone is overlain by a layer of residual sand and clay, ranging in thickness from 0 to 75 ft. This is material which was deposited as part of the limestone, but was not calcium carbonate-quartz grains, for instance. Since quartz is relatively insoluble, this material was left behind when the limestone dissolved. Thus, this residual layer indicates that hundreds of feet of limestone have dissolved here, leaving their insoluble components behind. The limestone surface below the sand layer is relatively porous and commonly contains small vertical tubes formed by solution at the intersection of two joints. These carry water downward. But, because the water can move rapidly down these open pipes, it can also wash some sand grains along with it. This creates a hollow in the unstable sand layer (fig. 7). The roof crumbles, and more sand is washed down the joint. The pocket continues to enlarge underground until the roof is too thin to support itself. Then sudden collapse occurs. This process may be accelerated or localized by man's alteration of the surface drainage, such as his directing more water to one area, thereby rapidly undermining it. An example of this in Albany, Ga., was the collapse on the Banks Haley Art Gallery grounds. This area acts as a collection basin for storm-sewer runoff. Water from the surrounding area is funneled into the basin and pumped out through sewer lines. On June 6, 1913, during an exceptionally heavy rain, one of the pumps failed to function properly, causing several feet of ponded water to soak into the ground. This infiltrating water triggered a sinkhole only 50 ft. from the gallery itself. Although conditions favorable to the natural formation of sinks exist throughout much of southwestern Georgia, data gathered over a two-year period indicate that the areas of active sinkhole collapse are centered around man's activities (J. D. Wilson, written commun., 1975). Urban development, which increases runoff by paving large areas, and heavy water withdrawals in a concentrated area are two key triggering mechanisms caused by man. Speleothems-Mineral Deposits in Caves When erosional downcutting of the outlets lowers the water level in a cave to a point that air may circulate within it, the process of speleothem growth begins. Speleothem is the geologist's collective term for all types of minerals that are deposited in a cave. Actually, certain types of speleothems are deposited underwater, but this water is generally in contact with air in the cave. Most speleothems are made up of the mineral calcite, which is crystalline calcium carbonate, the same mineral that makes up limestone. In fact, most speleothems are limestone redeposited in different forms. They accrete by reversing the same reaction which dissolved limestone. Remember that the soil has abundant carbon dioxide, much more than the air has. Thus, the water moving down into the ground becomes acidic, and dissolves limestone. However, when this water drips out onto the cave ceiling it comes into contact with cave air, which is similar to normal surface air. As a water droplet hangs on the cave roof, it slowly grows in size and loses carbon dioxide to the cave air. However, when this occurs, calcium carbonate must also be deposited, because the two are chemically balanced. 12 ~ lnaoluble sand and clay ~ Limutone Joints enlarged by solution A. Development of small caviti by washing sand down pipes ilil!1f~rf!ll1fll!1irirl B. Cavity enlargement by upward stopinv collapse and woshinQ away of debris lfrflji~fl:\i;rri11 C. Sinkhole development by sudden collapse- SinkhcM unstable llf~il'' D. Slopes of sinkhole reach stable angles as the sinkhole mature~ -~::.:~r~J~:~2;-;0ut~N{0L. Figure 7. Cross section showing progressive development of a collapse sinkhole in south Georgia. From what part of the water drop is the carbon dioxide lost? From the outside, of course. Then, where is the calcium carbonate deposited? In a tiny ring on the ceiling which marks the circle where the outside of the drop touched the roof. The next drop deposits another ring on top of the first one, and slowly a stalactite grows-a long, thin, hollow stalactite known as a soda straw (fig. 8). A. -joint - - - - .o.l./A~J~waf., deposHion of cole Of A\.\. CtN~RS .... :r ~opt ~ Figure 32. Georgia State Parks have a strict policy on cave exploring. Cartoon by Charlie Loving. Commercial Caves in the Georgia Area If caves interest you, but you are not quite sure if you want to grovel in the mud, try out one of the nearby commercial caves. There are none in Georgia, but there are several very nice ones in adjacent areas of Tennessee, Alabama, and Florida. The following list is provided through the cooperation of the National Caves Association, the nationwide organization of commercial cave operators. It may not be complete, and is not meant as an endorsement of caves on the list or as a criticism of any caves inadvertently left off the list. If you work with youth groups and you are interested in taking them caving, try Cumberland Caverns at McMinnville, Tenn. This is about an hour's drive north of Chattanooga. They have an exciting cave program, especially planned for young people. The group not only takes the commercial tour but also goes beyond the lights and trails-with a guide, of course. They follow this up with camping overnight inside the cave. The heavy gear is hauled into the cave by jeep through a rear entrance. Of course, a fee is charged, and advance arrangements are absolutely necessary. 39 Commercial Caves in the Georgia Area Alabama DeSoto Caverns, Childersburg Manitou Cave, Fort Payne Monte Sano State Park, Huntsville Rickwood Caverns State Park, Warrior Russell Cave National Monument, Bridgeport Sequoyah Caverns, Valley Head Florida Florida Caverns State Park, Marianna Ocala Caverns, Ocala Tennessee Bell Witch Cave, Adams Bristol Caverns, Bristol Caverns of the Ridge, Solway Cedars of Lebanon State Park, Lebanon Crystal Cave, Chattanooga Cudjo Caverns, Cumberland Gap Cumberland Caverns, McMinnville Forbidden Caverns, Sevierville Jewel Cave, Dickson Lost Sea, Sweetwater Natural Bridge (&Cave), Waynesboro Ruby Fails, Chattanooga Ruskin Cave, Dickson Tuckaleechee Caverns, Townsend Wonder Cave, Monteagle Figure 33. Cartoon by Charlie Loving. 40 Supplementary Reading The following books on various phases of speleology and cave exploring may be of interest to you. They are no substitute for learning from experienced teachers. The list is not intended to be exhaustive and no endorsement of any book is implied by its mention on this list. Many of these books are available at your local bookstore. However, almost all of them may be purchased by mail from the N.S.S. Bookstore at the N.S.S. office, or from Speleobooks, P. 0. Box 333, Wilbraham, Mass., 01095 (free catalog). General Books on Caves Caves, by Tony Waltham, 1974, Crown Publishers, New York, N.Y. $12.50, hardbound. A broad coverage, well illustrated. The Caves Beyond, by Joe Lawrence, Jr., and Roger Brucker, reprinted 1975, Zephyrus Press, Teaneck, N.J. $5.25, paperback. The story of a major early exploration effort by the N.S.S. Discovery at the Rio Camuy, by Russell and Jean Gurnee, 1974, Crown Publishers, New York, N.Y. $6.95, hardbound. Narrativeofexplorationin a large tropical cave. Available from the authors, 231 Irving Ave., Closter, N.J., 07624. Depths of the Earth-Caves and Cavers of the United States, by William R. Halliday, 1976, Harper and Row, New York, N.Y. $14.95, hardbound. Combines narratives and introductory cave science; a very broad coverage. The Jewel Cave Adventure, by Herb and Jan Conn, 1977, Zephyrus Press, Teaneck, N.J. $5. 95, paperback. A personal narrative of exploration and discovery in a major cave system in the United States. Under Plowman's Floor, by Richard Watson, 1978, Zephyrus Press, Teaneck, N.J. $7.95. A novel about a man who discovers caving and how it absorbs him. Excellent. Carlsbad, Caves, and a Camera, by Robert Nymeyer, 1978, Zephyrus Press, Teaneck, N.J. $14.95. Fascinating stories and pictures of early caving in New Mexico. The Longest Cave, by Roger Brucker and Richard A. Watson, 1976, Alfred A. Knopf, New York, N.Y. $12.50, hardbound. Narrative of explorations culminating in the connecting of two caves to make the world's longest cave. Absorbing reading. The World of Caves, by A. C. Waltham, 1976, G. P. Putnam's Sons, New York, N.Y. $12.95, hardbound. World-wide coverage of caves; introductory science; profusely illustrated. 41 V. I \) / ' J ) ., I f '\\ () \ I \ \ J( / 11 i \l ') ----.. -~~ i~ vtJ""'" Figure 34. Cave exploring techniques can only be learned from experience and practice, not from books alone. Cartoon by Thornton, courtesy of the N.S.S. News. How-To Books on Cave Exploring The Amateur's Guide to Caves and Caving, by David McClurg, 1973, Stackpole Books, Harrisburg, Pa. $3.95, paperback. Extensive coverage for beginners; prepared in cooperation with the N.S.S. Out-of-print, but check your library. American Caves and Caving, by William R. Halliday, 1974, Harper and Row, New York, N.Y. $10.00, hardbound. Coverage on techniques, equipment, and cave science with anecdotes. Of interest to both novices and experienced cavers; very detailed. Cave Exploring, by Jennifer Anderson, 1974, Association Press, New York, N.Y. $4.95,paperback. Very elementary and now out-dated. The Speleo-Guide, by John Slaven, 1971, published by the author, P.O. Box 3521, Visalia,Ca. 93277. $3.50, paperback. A very broad survey, but not detailed. Now very much out-dated. 42 Books on Speleology, the Science of Caves Cave Minerals, by Carol A Hill, 1976, The National Speleological Society, Huntsville, Ala. $15.00, hardbound. A somewhat technical, but profusely and beautifully illustrated coverage. Karst, by J.N. Jennings, 1971, MIT Press, Cambridge, Mass. $8.95, hardbound. Technical, but on an introductory level; broad. Karst Landforms, by Marjorie Sweeting, 1973, Columbia University Press, New York, N.Y. $25.00 hardbound. Technical, broad,well illustrated; reader should have background in geology. The Life of the Cave, by Charles Mohr and Thomas Poulson, 1%6, McGrawHill, New York, N.Y. $4. 95, hardback. Profusely illustrated coverage of cave biology in layman's terms. Out-of-print, but most libraries have it. The Science of Speleology, by T.D. Ford and C.H.D. Cullingford,eds., 1976, Academic Press, London, England. $29.50, hardback. Thorough, but highly technical; for professional scientists; covers both biology and geology. Speleology, the Study of Caves, by George Moore and Brother G. Nicholas, reprinted 1976, Zephyrus Press, Teaneck, N.J. $4.50, paperback. Introductory, in layman's terms; broad; some areas recently revised. Geology and Biology of Pennsylvania Caves, by William B. White, and John R. Holsinger, 1976, The Pennsylvania Geological Survey, Harrisburg Pa., 17125. White's treatment of the geology and hydrology of caves is not restricted to Pennsylvania and is well written, but it requires some technical background. Well worth the $2.00. Acknowledgements Credit for all photographs and diagrams is noted in the captions. If none is noted, they are by the author. All cartoons, unless specifically noted otherwise, are from "My Daddy was a Caver" by Charlie Loving, Speleo Press, P.O. Box 7037, Austin Tx., 78712 ($1.25 PP.) It contains many caving cartoons in addition to those used herein. Much of the organization and many of the ideas used in this booklet were stimulated by a slide-tape presentation on caving prepared by a committee of members of the Dogwood City Grotto, including the author. References 1. Aley, Tom, 1974, Ground water problems in southwest Missouri and northwest Arkansas in Missouri Speleology, vol. 14, no. 2, p.1-21. 2. Krause, R. E., 1976, Occurrence and distribution of color and hydrogen sulfide water from the principal artesian aquifer in the Valdosta area, Georgia. U.S. Geological Survey Open-File Report 76-378, 12 p. 3. Wilson, J. D., 1975, Georgia Geologic Survey, Department of Natural Resources, Albany, Georgia. 43