Underground life digs into imagination

Cave formations

Cave of the Mounds is home to numerous formations.

• Canopy forms when the base material – silt, clay or gravel – is washed out from underneath flowstone leaving an unsupported, hanging deposit.

• Cave coral is a general term for speleothems with branching stems and nodular tips. Usually formed by seeping water, it often resembles sea coral, broccoli or cauliflower in appearance. It’s also known as cave popcorn.

• Cave pearls are deposits formed around a sand particle or other mineral fragment. The particle becomes encased within mineral layers that slowly accumulate into rounded pearls. They’re also called oolites.

• Column refers to any formation connecting the ceiling to the floor in an unbroken mass.

• Flowstone is a surface coating of mineral deposited by water flowing downward from a source.

• Helictites are small twisting calcite structures that project from the walls of other cave deposits in curiously shaped, fragile forms. They’re thought to be formed by pressurized water within the stalactite seeping through a crack in the formation.

• Ribbon stalactites – cave bacon or drapery – form when a drop of water flows down an inclined ceiling and deposits a ribbon-like trail of minerals that is often thin, banded and translucent.

• Rimstone dams are cave deposits that dam water on cave floors. They usually occur in a series of curved steps that hold back water in crescent-shaped pools. Water normally overflows from one pool to the next.

• Shelfstones or cave rafts form from a thin floating film of mineral on a cave pool. If the surface of the water is disturbed, the cave rafts slowly sink to the bottom of the pool. At the margins of some cave pools, deposits attached to the wall grow out over the water, creating a shelf.

• Shields form where water seeps into the cave through the ceiling, wall or floor. They’re semicircular in shape and attached along the straightest edge.

• Soda straws are thin-walled, hollow stalactites that lengthen as minerals are deposited in a ring at the edge of a drop of water in contact with the ceiling of the cave.

• Splash basins are cup-shaped ridges deposited on stalagmites from dripping water.

• Stalactites are deposits that grow downward from the ceiling of a cave.

• Stalagmites are deposits that grow upward from the floor of a cave.