Caves are underground landscapes formed by the forces of erosion. Carbonic acid in water dissolves rock and forms passages and mineral formations. Caves cover 10% of the earth and occur in temperate, tropical, alpine and polar biomes. They are called Karst landscapes. About 1/4th of the world's people depend on water supplied by karst areas.
Discover the wonder of karst regions. Subjects include caves, cave pearls, columns, dripstone, flowstone, soda straws, stalactites and stalagmites. The Early Childhood version has 8 subjects and 32 cards.