Popcorn and Pearls,
Beetles and Bats
Key to Poster
Somewhere in the distance, a bat squeaks . . . but only the bat and others like it can hear the sound. Nothing in the equipment the cavers (1) have will enable them to hear the high-pitched frequency of the bat's cry. But they forge on, ready to explore this unusual world. Whatever one's interest—creatures or features—caves have much to offer.
Creatures abound: troglobites include the blind crayfish (10) and blind harvestman spider (8), a subterranean daddy longlegs. Other fauna, such as cave salamanders (9) and cave crickets (11) are troglophiles. Then there are the trogloxenes, of which bats, such as the little brown bat (5), are examples.
Caves are also a special place for unique geological features (speleothems) that range from the massive to the delicate.
Stalagmites (6) are upward-growing calcite cones made from dripwater deposits. Stalactites (4) are downward-growing cones, also made from dripwater deposits. Stalactites begin as soda straws (14), hollow tubes that grow downward and conduct water externally as well as internally through their cores. When stalactites and stalagmites join together, columns (2) are formed. Caves also host draperies (3) (some of which may be referred to as "cave bacon" by the more culinary minded), which form when calcite-rich solutions flow along overhanging surfaces.
Another speleological food feature is cave popcorn (16), made up of concentrically layered microcrystalline calcite. If jewelry is more to your taste, there are cave pearls (7), concentric concretions found in shallow cave pools. They can be spherical, cylindrical, elliptical, or cubical. And when you're exploring caves, don't forget to stop and smell the cave flowers, which are usually made of gypsum (13), with crystal petals that radiate from a central point and grow from the base. Water, critical to the formation of limestone caves, is often present as pools or lakes (17). When it flows, it helps form flowstone, which can be massive (15) or delicate (knobby) (12). Caves: really cool places, and definitely something to squeak about—even if you're not a bat.