Dark Roasted Blend: Caves: The World Beneath the World
http://www.darkroastedblend.com/2008/10/caves-world-beneath-world.html

Enter a narrow natural passageway that may lead to simply mind-boggling underground world - to get away from the depressing sights like these... Caves may lurk right under your feet: a fascinating and unexpected environment, which is often known only to spelunkers and dedicated Gollum-seekers.

Some of the cave and rock formations: - Flowstone (also known as a Bacon formation) - Cave Pearls - Soda Straws