Alabama is home to a diverse and widespread variety of minerals. Chalk, a soft, extremely fine-textured variety of limestone, occurs in the Coastal Plain section of west-central Alabama. Originally formed as the floor of an ancient sea, the chalk can be seen along prominent bluffs on the Tombigbee River. White Bluff is a historic site located in Demopolis, AL, which owes its character and natural beauty to the underlying chalk rocks.