Black Chasm Cave Black Chasm Cavern are derivative of the marble bedrock, containing primarily calcium or calcium carbonate (CaCO3). There are a variety of formations in Black Chasm Cavern, including stalactites, stalagmites, columns, flowstone, draperies, ribbons, angel's wings, cave bacon, soda straws, helictites, false floors, and others. Black Chasm Cavern is home to amphipods, which live in the lakes of the cave. The amphipods are adapted to life without light, having no pigmentation or eyesight. Also living within the cave, and adapted to total darkness, is the Banksula grubbsi arachnid. Related to the harvestman, the Banksula grubbsi has a multi-segmented body that appears
Cave of the Mounds National Park Service designated the cave as a National Natural Landmark. The limestone from which the cave was carved began forming approximately 488 million years ago, during the Ordovician Period. During this time, much of North America was covered with warm, shallow seas. Over millions of years, calcium carbonate shells from tiny marine organisms accumulated on the sea floor, forming enormous quantities of limestone. The type of limestone in which the cave was formed is called galena dolomite because of its high concentration of the lead ore galena. The cave began forming about a million to a million and a