You are a US citizen and: 1  You are a first time applicant age 18 or older. 2  OR your most recent U.S. Passport was issued when you were under age 16. 3  OR your previous U.S. passport was issued more than 15 years ago.
Cave formations are called speleothem, from the Greek word spelaion, cave and thema meaning deposit. Almost all of them are made of calcite, the crystal of calcium carbonate. Different minerals and different movements in the water account for an incredible variety of cave formations.
The calcium carbonate then goes into the ground water which moves down farther into the cave. The water will find its way into small crack and crevasses. The dripping water will create formations called stalactites and stalagmites. Stalactites (they grow from the ceiling)and stalagmites (they grow from the floor) are not technically limestone. They form in caves because as the limestone is dissolved calcium carbonate is put into solution in the ground water. This solution drips through crack and slowly forms stalactites and stalagmites.