Solutional Caves Commonly Begin with Begin with Commonly Caves Solutional Filled, Lying Water at Initially Is Completely a Cave

. Also, conditions. breakdown vadose (water-filled) conditions. Later, if the Later, conditions. (water-filled) . The resulting. The pool upstream from the dam phreatic As water continues to flow through to continues As the air-filled water

Cave formations (speleothems) that hang down from the ceiling of Cave formations (speleothems) that hang down from made of calcium carbonate. called stalactites and are a cave are known as The will partly be drained. cave the falls, table water part the lower occupying remaining the cave of water forms a stream, similarthis a surface stream. Once to is then stream the cave is formed, enlargement of usually the stream erosion limited of to bed. These called are conditions air-filled mostly The stream commonly cuts a vadose canyon below the below streamThe a vadose cuts commonly canyon original part phreatic lower tube. The this will of canyon in areas gravel and where mud, beoften refilled clay, by This canflow occur slowed. upstream a pile has of of as known rock, wall or ceiling collapsed where a stream flows over an irregularity a streamwhere flows over in the floor sometimes forming depositsit a calcium carbonate, dam rimstone can then fill with sediments as well. carbonate calcium deposits often it cave the part of stalactites, as such speleothems of form the in stalagmites, rind, bacon soda and flowstone. straws, dripping from theWater stalactites tips (hanging of build which stalagmites, form can ceiling) the from drip fromupward drip. Publicly the floor, by accessible Mike Bounk Mike 15 feet, the minimum feet, distance to 15 to exist in Iowa. They vary exist They to in Iowa. in length from pproximately one thousand caves are thousand one known caves pproximately

Solutional caves commonly begin with begin with commonly caves Solutional filled, lying water at Initially is completely a cave

A miles long, in the 17 over to be a cave, considered in Winneshiek Cave County, Water case Cold of average the longest The known in the state. cave 48 degrees is about air caves in Iowa temperature are mainly located Caves in easternFahrenheit. and northeastern form and in Iowa carbonate rocks through dolomite) and (limestone solution slightly the rock host of by groundwater. acidic sinkholes results of in the solution formation Such (naturally occurring rock depressions solution to due disappearing areas of caves, or collapse), drainage (stream flows other with and surface outlet), no karst solutional creating a landscape features, of Karst to due can also form mechanically, topography. blocks the rock host carbonate of gradually sliding on shale. underlying Caves Solutional groundwater moving through fractured limestone (calcium (calcium carbonate) or dolomite magnesium This groundwater dissolvedcarbonate). contains carbon from up dioxide the air gas picked soil, and is carbonic of that forming acid solution a weak dissolving of As time. capable rock over carbonate through moves the rock, usually following water fractures bedding and dissolves planes, it the rock widens and theseadjacent fractures or bedding flows Asplanes. water fractures more wider, become through resulting conduits them, of in the creation is a passageway large A cave and passageways. a personenough for enter. to In cross table. a newly section, the water or below is typicallyformed cave circular Water or elliptical. flows through as through it dissolving a pipe, the rock outward in all directions. are These are what

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CAVES CAVES www.igsb.uiowa.edu FRONT COVER 109 Trowbridge Hall 109 Trowbridge Photo by Mike Bounk Photo by Mike Geological Survey Iowa City, Iowa 52242-1319 Iowa City, Educational Materials: EM-41 (2005) in Cold Water Cave, Winneshiek County. County. Cave, Winneshiek in Cold Water A caver studying stalactites and stalagmites Iowa Department of Natural Resources Cold Water Cave, Human Uses shown in both photos, Prehistoric humans used caves in Iowa for shelter. Mike Bounk Mike contains spectacular Bounk Mike speleothems, in- Even today, prehistoric pictographs can be seen on cluding stalactites, the walls of some caves. Later uses have included stalagmites, bacon the mining of lead and zinc ores from caves in the rind, soda straws, and flowstone. Note Dubuque area, and obtaining ice from ice caves during the detailed texture of the summer. Water flowing from springs (presumably the flowstone and the depth of the stream fed by caves) has been used to run mills and supply (about 3 feet) in the fish hatcheries, such as the hatcheries at Siewers close-up photo to Springs near Decorah and Big Spring near Elkader. Cold the right. Water Creek, which the Iowa Department of Natural Resources stocks with trout, originates from Cold Water Cave. Popular public use areas exist around caves, such as Dutton’s Cave County Park near West Union and Maquoketa Caves State Park near Maquoketa. Caves are visited by cavers both for recreation and scientific studies, such as mapping, water quality research, and cave development, as well as studies to understand climate change.

Conservation Never disturb anything in a cave. A damaged formation will take thousands of years to repair itself, if ever. In the case of an actively growing formation, even touching it or getting mud on it can cause damage. caves in Iowa with actively growing formations include influence of gravity, sliding and often rotating out Don’t leave trash, litter, or anything else behind. Also, Get proper training. Locate a group of exper- Spook Cave near McGregor and Crystal Lake Cave near from the main outcrop, creating abundant sinkholes, be sure not to disturb bats during their hibernation ienced cavers, commonly known as a grotto, in your Dubuque, two commercial caves. The best example underlying fracture networks, and caves along most from October to March, as they can die if disturbed. area. These knowledgeable cavers can teach you is Cold Water Cave, which is almost entirely privately of the escarpment. In winter, cold air flowing through specialized skills such as rope work, which is done owned and not normally accessible to the public. this network cools the rock. In spring, snowmelt and Safety on special low stretch ropes, not with clothesline or rainwater enter these openings, sometimes freezing, Caves can be very dangerous. Never cave alone. hardware rope. Mechanical Caves and in the summer, chilled air flows from these slopes. Always make sure someone knows where you are going To find your local grotto, contact the National The karst terrain in which mechanical caves are This results in what are termed algific slopes, which and when you will be back. Take proper equipment, Speleological Society, 2813 Cave Avenue, Huntsville, produced occurs along the Silurian Escarpment (a ridge harbor vegetation not normally found this far south, including a hard hat, multiple light sources, gloves, Alabama 35810, (telephone 256-852-1300, email of 430 million-year-old dolomite running northwest to as well as species of vegetation remaining from the boots equipped with cleats, and warm clothes that can [email protected]). Visit their web site at www.caves.org southeast through southern Clayton, Dubuque, and last ice age (which ended approximately ten thousand insulate even when wet. Proper clothing can include a northern Jackson counties), as well as in other areas years ago). A few caves in these slopes contain ice far full wetsuit. Listen to weather forecasts and heed them. of northeast Iowa. Water seeping down through the into the summer. The best known example is Decorah Never go into an unknown cave or one that is likely to dolomite lubricates the underlying shale and softens Ice Cave, which occurs well north of the Silurian flood when rain or snowmelt may occur, as caves can it. This can result in blocks of dolomite, under the Escarpment. flood quickly.