File:Travertine speleothem (Bridal Altar, Gothic Avenue, Mammoth Cave, Kentucky, USA) 2 (37696037924).jpg

(from an old postcard)

Western Kentucky's Mammoth Cave is the longest cave system on Earth, with 412 miles known and mapped as of fall 2017. 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.

In this photo, a cluster of travertine columns is present - this is the "Bridal Altar". Early literature reports that 16 weddings have taken place here.