Cave popcorn

Wide angle view of cave popcorn

Cave popcorn, or coralloids, are small nodes of calcite, aragonite or gypsum that form on surfaces in caves, especially limestone caves.^[1]^[2] They are a common type of speleothem.^[1]^[2]

Appearance

The individual nodules of cave popcorn range in size from 5-20 mm and may be decorated by other speleothems especially aragonite needles or frostwork.^[1]^[2] The nodules tend to grow in clusters on bedrock or the sides of other speleothems.^[1] These clusters may terminate suddenly in either an upward or downward direction forming a stratographic layer.^[1] When they terminate in a downward direction, they may appear as flat bottomed formations otherwise known as trays.^[1]

The color of cave popcorn is usually white but various other colors are possible depending on the composition.^[2]

Formation

Cave popcorn can form by precipitation by the loss of CO₂.^[1] Also it is fromed by the seeping of water through limestone walls or splashing into the caves. Then the water deposits minerals, such as calcite, in bumpy lumps. When formed in this way the nodules have the characteristics of small balls of flowstone.^[1] It can also form by evaporation in which case it is chalky and white like edible popcorn.^[1] In the right conditions, evaporative cave popcorn may grow on the windward side of the surface to which it is attached or appear on the edges of projecting surfaces.^[1]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Palmer, Arthur N. (2007). Cave Geology. Dayton, OH: CAVE BOOKS. p. 288. ISBN 978-0-939748-66-2.
^ ^a ^b ^c ^d Hill, Carol; Forti, Paolo (1997). Cave Minerals of the World (Second Edition ed.). Huntsville, AL: National Speleological Society. pp. 59–61. ISBN 1-879961-07-5.

3. "Cave Popcorn or Coral." Underground Adventures. Sierra Nevada Recreation Corp,

    2006. Web. 2 May 2012. <http://www.caverntours.com/ 
    KIDSPAGE_Form_Popcorn.html>.

4. Horsted, Paul. Cave Popcorn with Frostwork. N.d. National Park Service. U.S.

    Department of the Interior, n.d. Web. 3 May 2012. <http://www.nps.gov/ 
    wica/naturescience/speleothems-cave-popcorn.htm>.

External links

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[PALMER-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Palmer, Arthur N. (2007). Cave Geology. Dayton, OH: CAVE BOOKS. p. 288. ISBN 978-0-939748-66-2.

[HILL-2] Hill, Carol; Forti, Paolo (1997). Cave Minerals of the World (Second Edition ed.). Huntsville, AL: National Speleological Society. pp. 59–61. ISBN 1-879961-07-5.

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