Special Places

Cave Formations

Calcite is dissolved from the limestone when surface water, containing carbonic acid absorbed from the air and soil, percolates down through the rock and into the cave. When this acid water - carrying a calcium bicarbonate solution - encounters the air inside the cave, the carbon dioxide is released. The water then deposits the calcite. Layer upon layer of calcite deposit will eventually shape the speleothem.

Many factors determine the shape that speleothems will take. How the acid water enters the cave - by dripping, flowing, seeping, splashing - and how it flows or stands after entering, are just two of these factors.

Sometimes the calcite speleothems have pastel and earth colors, indicating that other minerals were deposited, continuously or at intervals. Iron oxides account for the shades of brown, yellow, and red, while manganese gives shades of blue, black, and gray.

  • Soda straws (first stage stalactites) grow from the ceiling as water runs down inside them and deposits rings of calcite at their tips.
  • When the soda straws are plugged, water trickling down their outside turns them into larger carrot - or icicle - shaped stalactites .
  • Stalagmites , which rise from the floor when dripping water deposits minerals, are usually larger in diameter than stalactites and more rounded on top.
  • A stalactite and stalagmite may meet midway, forming a column . Or, one or the other may grow all the way to the floor or ceiling to form a column.
  • On an inclined ceiling, water may deposit calcite in thin, translucent sheets, producing draperies that hang in delicate folds.
  • At times, water forming the draperies contains minerals in addition to calcite, resulting in dark orange or brown bands called bacon formation .
  • A flowstone forms when considerable water flows down walls, over floors and older formations, building up sheets of calcite like icing on a cake.
  • Along streams, rimstone dams and terraces often build up and trap the water in pools - the home of tiny blind, white creatures that dwell in caves.

The Coral Pond is a highlight of the Dripstone Trail. This material is not really "coral" at all, but calcite. These lacy patterns are formed on top of calm waters at the point of air contact. As the water levels slowly rise and fall, different calcite levels are deposited.