Flowstone is composed of sheetlike deposits of calcite formed where water flows down the walls or along the floors of a cave. Found in "solution", or limestone caves, it is the most common of all speleothems.

Flowing films of water that move along floors or down positive-sloping walls build up layers of calcium carbonate (calcite), aragonite, gypsum, or other cave minerals. These minerals are dissolved in the water and are deposited when the water loses its dissolved carbon dioxide, meaning it can no longer hold the minerals in solution. The flowstone forms when thin layers of these deposits build on each other, sometimes becoming rounder as the deposit gets thicker.

Sometimes the deposits are so wide and thin they are called "draperies", and many deposits look like static waterfalls. Some are translucent, and some have brown and beige layers that look much like bacon (often termed "cave bacon").

Though flowstones are among the largest of speleothems, they can still be damaged by a single touch. The oil from human fingers causes the water to avoid the area, which then dries out.

See also

• Karst