Why do some divers risk life and limb to explore caves, often in remote areas of the world? Partly, it’s because of the thrill associated with diving in a place few eyes have seen, and in part, it is because caves are spectacular for their geology, which shows us how the earth shapes and reshapes itself as we pass time above the surface. Here are just a few of the many different types of formations you might see inside caverns, should you ever make the decision to become a qualified cave diver.
Stalactites
Formed when water drips or flows through cracks in cave ceilings, stalactites hang suspended and continue to grow so long as nothing impedes the water’s path. Shaped like cones with irregular surfaces, these formations are capable of growing at the rate of about half an inch per hundred years. Stalactites that are underwater have stopped growing for the time being, although if they are exposed to cavern air at some point in the future, they might resume growth. Stalactites that are suspended above cave basins, though, are often in active growth and should never be touched.
Soda Straws
Actually the early formative stages that show us where stalactites will grow, soda straws are small, hollow cave formations with very thin walls. It is unusual to find these underwater as they are extremely fragile, but in actively growing cave systems, you can often see them suspended over open water, often dripping or even trickling as they grow. Over time, soda straws are plugged by sediment, at which point they are considered to be stalactites.
Stalagmites
Usually positioned directly beneath stalactites, stalagmites are shaped like inverted cones, and are formed as water droplets from stalactites drip down onto their surfaces. In deep, active caves, it is not unusual to see large stalactites hanging from the ceiling, with much smaller stalagmites beneath the water’s surface.
Pillars
Scientists estimate that large pillar formations can take as long as millions of years to form, simply because of the slow growth rate of stalactites and stalagmites. Pillars are formed when these smaller formations join at their tips
Flowstone
Deposits of calcite shaped like curving sheets, flowstone can sometimes hug cavern walls. Sometimes hanging suspended and often curving magnificently, flowstone sometimes forms additional cave formations called bacon strips. These often display light and dark stripes that cause them to resemble a strip of bacon; sometimes, they are thin enough to be translucent, so a light shining through from one side can be easily seen from various angles. Often, you’ll see flowstone in active caves. It’s shiny appearance comes from the thin layer of water that runs down its surface. That water then goes on to feed the underwater environment you’re diving in.
The type of formations you’ll see inside caves will vary according to cave composition. For example, there are no stalactites or stalagmites inside Ordinskaya Cave in Russia, simply because its brittle gypsum formation does not encourage growth. On the other end of the spectrum, Chac Mol, located south of Playa del Carmen has beautiful formations and boasts the largest known underwater stalactite in the world.