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Geology of Mojave National Preserve: Mitchell Caverns

The lighted interior of Mitchell Caverns
The spectacular decorations of Mitchell Caverns form one drip at a time.

Dripping decorations

Dripstone decorations form during the final stage in cave development, after the water table lowers. Spaces formed in the rock when the water table was higher are left high and dry as the cave drains. Air fills the cavities and calcite decorations can begin to deposit.

Water picks up calcite and carbon dioxide as it trickles down through pores and cracks in the limestone above the cave. When the carbon dioxide enriched water reaches the open cave, the carbon dioxide gas escapes from the water, almost like opening a can of soda. This reduces the acidity in the water so that calcium bicarbonate cannot remain dissolved in the water. Microscopic layers of calcite are deposited drip by drip, forming intricate dripstone decorations.

 

The lighted interior of Mitchell Caverns
The lighted interior of Mitchell Caverns.

Speloethems

Dripstone features in caves are called speleothems (from the Greek spelaion for cave and theme for deposit). Electric lighting in Mitchell Caverns transforms the speleothems into beautiful and eerie forms.

Stalactites. Notice that some of the stalactites have been broken, exposing their hollow interior structure
Stalactites. Notice that some of the stalactites have been broken, exposing their hollow interior structure.

Stalactites, stalagmites and more

Stalactites grow downward from the cave roof. Like other cave formations, they form as water slowly drips through cracks in the cave ceiling. While each water drop hangs from the ceiling, it deposits a calcite film. After many thousands of years and drips, an intricately decorated hanging cone may form. Tubular or "soda straw" stalactites grow in much the same way. Soda straws are among the most fragile cave decorations. They may reach up to a yard in length, but have the diameter of a drop of water. Large stalactites begin as these tiny soda straw tubes,then gradually enlarge when water flows outside of the soda straws.

Stalagmites grow upward from the cave floor water when water drips from overhanging stalactites or other ceiling decorations. In some cases, stalactite and a stalagmite grow until they join, forming a column. Cave drapery can form on sloped cave ceilings when the drops of water trickle along an incline. A thin, curtain-like sheet of calcite may grow along the slope, creating fragile, translucent draperies.

Stalagmites
Mitchell Caverns stalagmites

Sheets of calcite deposited on walls or floors by flowing water are called flowstone. Rimstone dams are raised fence-like deposits of calcite on the cave floor that form around pools of water.

Mitchell Caverns preserves excellent examples of these amazing cave decorations. See more in our image gallery.

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Mitchell Caverns image gallery
General information on caves
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