Stalactites (from the Greek stalaktos, ‘oozing out in drips’) hang from cave ceilings. Water oozes out of cracks in the ceiling and as it evaporates it leaves behind tiny deposits of calcium carbonate. Initially these create hollow tubes. Eventually the tubes clogs up, and water runs down the outside, creating the typical stalactite shape.
Cave Location Details
Mammoth Cave System: Kentucky, USA: Longest cave system, 550 km (340 miles) of chambers & passages.
Krubera: Georgia: Deepest discovered-1710m (1mile) deep. Discovered in 2002.

Doctors in the west continued to influence each other but knew nothing of the Chinese approach. After the fall of Rome in the fifth century AD, there was no medical teaching in Europe, but the Arabs studied and translated many Greek manuscripts, making useful additions of their own. Rhazes (865-925), chief physician at the hospital in Baghdad, was the first to distinguish between smallpox and measles. The medical works of the Persian writer Avicenna (980-1037) were compulsory reading for European medical students until about 1650.