English: Western Kentucky's Mammoth Cave is the longest cave system on Earth, with 426 miles known and mapped as of March 2024. The name does not refer to the early discovery of fossil mastodon or mammoth bones here. Rather, the name refers to the immense size of many rooms and passages.

Speleothem (= "cave formations") refers to all secondary mineral deposits in caves. Most speleothem is composed of calcium carbonate (CaCO3 - usually in the form of calcite, but sometimes aragonite). Calcareous speleothem is referred to using the rock name "travertine", a crystalline-textured, chemical sedimentary rock formed by precipitation from water.

Dripstone and flowstone are the most common forms of travertine speleothem. Dripstone forms by calcium carbonate precipitation from dripping water. Flowstone forms by calcium carbonate precipitation from thin sheets of flowing water. The most common forms of dripstone are stalactites (attached to ceilings), stalagmites (growing from the floor), columns (= fused stalactite-stalagmite pairs), and draperies (= curtain-like sheets formed as water drops descend along an inclined surface). Flowstone often has the appearance of frozen waterfalls.

Seen here is a cave ceiling with stalactites and soda straws. Soda straws are slender, cylindrically-shaped stalactites. These speleothem are still actively forming - water drops are present at their tips. I see at least 20 cave crickets on the ceiling (click once or twice on the photo to zoom in and look around). They sometimes drop down onto unsuspecting tourists' heads.

Locality: limestone ceiling at Violet City, southeastern end of Main Cave, Mammoth Cave Ridge, western Kentucky, USA

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(accessed with park permission)