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Crystal Grottoes is the only show cave in the U.S. state of Maryland. It is located on Maryland Route 34 between Boonsboro and Antietam National Battlefield.
Crystal Grottoes was discovered in 1920 in the course of quarrying operations by a road construction crew trying to obtain gravel. [1] A drill bit (for placing explosives) disappeared into a hole, and the crew realized they had found a cave. Blasting produced the entrance which is still used, and in 1922 the cave was opened to the public. A mapping operation in 1968 revealed about a half mile of passages, but only about one third of the cave is accessed during the tour, which takes about 30–35 minutes.
Crystal Grottoes is an example of a solutional cave, formed in a karst environment within a synclinal occurrence of Tomstown Dolomite. The cave is essentially horizontal throughout its extent and the passages are typically high and narrow. A great deal of brown and red clay fills most of the cave to a considerable extent; the commercial tour routes involved the removal of up to 4–6 feet (1.2–1.8 m) of this clay in 900 feet (270 m) of the passages. Sediment fills many of the undeveloped passages to within a foot or two of the ceiling, thereby making many crawlways. No streams exist in the cave, although a small "lake" or pool is maintained by drip water.
Most of the rooms abound in speleothem formations, generally stalactites, flowstone, and columns. They are typically white or buff, with one area (called Fairyland) tinted a light red, by iron oxides.
The first room is 8 feet (2.4 m) below the entrance house and is oblate in shape, being 30 feet (9.1 m) long, 10 feet (3.0 m) wide, and 15 feet (4.6 m) high. At each end it is pinched out by mud flows and narrowing of the passage. This room originally contained a considerable number of formations, but quarrying operations and clearing of passages have removed them except along the west wall where flowstone and stalactites are abundant.
The passages are continuously lined or covered by formations. Delicate draperies, bacon, and columns predominate. The colors are generally pure white or buff with occasional deeper tints. The passages forming Fairyland are studded with stalactites and stalagmites of a delicate light red hue.
The Blanket Room is the largest room in the caverns at 30 feet (9.1 m) long and 20 feet (6.1 m) wide. Large sheets of stalactites and draperies hang in clusters from the ceiling, which is here 20 feet (6.1 m) high.
The passage leading to the lake is profuse with formations and in part is bridged by flat-lying travertine, a condition that is found in many of the passages not open to the public. The lake is a small pool fed by water dripping from the ceiling. In wet seasons the water accumulates at a rate necessitating periodic bailing.
The passages not open to the public are similar to those already described except they are constricted at many points. Orange-brown clay that covers the floor and lower walls of these passages is often overlain by calcareous formations. The commercial tour route covers approximately one third of the known cave. [2]
A stalactite is a mineral formation that hangs from the ceiling of caves, hot springs, or man-made structures such as bridges and mines. Any material that is soluble and that can be deposited as a colloid, or is in suspension, or is capable of being melted, may form a stalactite. Stalactites may be composed of lava, minerals, mud, peat, pitch, sand, sinter, and amberat. A stalactite is not necessarily a speleothem, though speleothems are the most common form of stalactite because of the abundance of limestone caves.
A stalagmite is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites are typically composed of calcium carbonate, but may consist of lava, mud, peat, pitch, sand, sinter, and amberat.
Crystal Cavern(s), also known throughout the years as Alabama Caverns and McClu(n)ney Cave, is a small cavern containing crystal formations located in Clay, Alabama, USA.
The Natural Bridge Caverns are the largest commercial caverns in the US state of Texas. The name is derived from the 60-foot (18 m) natural limestone slab bridge that spans the amphitheater setting of the cavern's entrance. The span was left suspended when a sinkhole collapsed below it.
A speleothem is a geological formation by mineral deposits that accumulate over time in natural caves. Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a variety of forms, depending on their depositional history and environment. Their chemical composition, gradual growth, and preservation in caves make them useful paleoclimatic proxies.
Luray Caverns, previously Luray Cave, is a cave just west of Luray, Virginia, United States, which has drawn many visitors since its discovery in 1878. The cavern system is adorned with speleothems such as columns, mud flows, stalactites, stalagmites, flowstone, and mirrored pools. The caverns host the Great Stalacpipe Organ, a lithophone made from solenoid-fired strikers that tap stalactites of varied sizes to produce tones similar to those of xylophones, tuning forks, or bells.
At 150.4 miles (242.0 km), Lechuguilla Cave is the eighth-longest explored cave in the world and the second deepest in the continental United States. It is most famous for its unusual geology, rare formations, and pristine condition.
Flowstones are sheetlike deposits of calcite or other carbonate minerals, formed where water flows down the walls or along the floors of a cave. They are typically found in "solution caves", in limestone, where they are the most common speleothem. However, they may form in any type of cave where water enters that has picked up dissolved minerals. Flowstones are formed via the degassing of vadose percolation waters.
Treak Cliff Cavern is a show cave near Castleton in Derbyshire, England. It is part of the Castleton Site of Special Scientific Interest and one of only two sites where the ornamental mineral Blue John is still excavated. As part of an agreement with English Nature, the Blue John that can be seen in the show cave is not mined but it is extracted in small quantities from other areas of the cave and made into saleable items like bowls, jewellery, and ornaments.
Cave of the Winds is a cave in the Pikes Peak region of Colorado. It is located just west of Colorado Springs on U.S. Highway 24, near the Manitou Cliff Dwellings. Tours of the complex of caves are given daily.
Illinois Caverns is a state natural area in the New Design Precinct of Monroe County, Illinois. It features Illinois Caverns which is alternatively known as Mammoth Cave of Illinois. Illinois Caverns is the second-largest cave in Illinois and has more than 9.6 km of passages. The cave has a constant temperature of 58 °F (14 °C), and portions flood during wet weather. Passages can be 20 feet (6.1 m) high and just as wide. It is located off Illinois Route 3, south of Waterloo, near the unincorporated community of Burksville.
Cumberland Caverns is a national natural landmark and show cave located in McMinnville, Tennessee. It is the second longest cave in Tennessee and makes the list of longest caves in the United States and in the world.
Black Chasm Cavern is a cave in the hamlet of Volcano in Amador County, California.
Carlsbad Caverns National Park is an American national park in the Guadalupe Mountains of southeastern New Mexico. The primary attraction of the park is the show cave Carlsbad Cavern. Visitors to the cave can hike in on their own via the natural entrance or take an elevator from the visitor center.
Grand Caverns, formerly known as Weyer's Cave, is located in the central Shenandoah Valley in the town of Grottoes, Virginia, United States. A limestone cavern, it claims the distinction of being America's oldest show cave, in operation since 1806.
Boyden Cavern is a show cave located in the Giant Sequoia National Monument of the Sequoia National Forest, along the Kings Canyon Scenic Byway in Fresno County, California. It is just west of Kings Canyon National Park.
The Lake Shasta Caverns are a network of caves located near the McCloud arm of Shasta Lake in California. It was formerly named Chalk Cave and Baird Cave, named after Spencer Fullerton Baird.
Gruta de Maquiné (MG-0243), also Lapa Nova de Maquiné, is the oldest and one of the most commercially visited caves in Brazil. It is located about 5 km (3.1 mi) from Cordisburgo and 143 km (88.9 mi) northwest of Belo Horizonte, in the State of Minas Gerais. The cave has seven huge chambers explored, amounting to 650 m (2,130 ft) (linear) and unevenness of the ground of only 18 m (59 ft). Safety measures like lighting, walkways and handrails allow a multitude of visitors to enjoy safely the wonders of the grotto where the whole journey is accompanied by an experienced local guide.
Calcite crystals form on the surface of quiescent bodies of water, even when the bulk water is not supersaturated with respect to calcium carbonate. The crystals grow, attach to one other and appear to be floating rafts of a white, opaque material. The floating materials have been referred to as calcite rafts or "leopard spots".
