1001 Space Earth Earth Rocks and Minerals Landscape Sea Weather and Climate Natural Disasters Resources Nature History Human World Science and Technology

Choose a Page:What is the rock cycle?What is weathering?What shapes the cliffs along the s...Do rocks dissolve?Can living things break down rocks?*How are caves made?*How do sand dunes move?Why do desert rocks have fantastic...How do rivers form?What makes waterfalls?What is scree?What is an oxbow lake?Is all erosion slow? How are caves made? Rainwater absorbs carbon dioxide gas from the air, which makes it acidic. The acid attacks some kinds of rocks, particularly limestone. A limestone bed can be hollowed out by the acidic water passing through it. Weak areas, such as cracks or the gaps between beds, are eroded first, forming horizontal caves along the water table. The water table is the level at which the rocks are saturated with water. When the water table changes, different levels of caves are hollowed out. Rainwater flowing underground can hollow out rocks such as limestone and form caves.   Previous: Back Book: 1001 Section: Earth Chapter: Landscape