Groundwater Erosion
Groundwater is the term geologists use when rain falls and snow melts, but not all of the water evaporates or turns into runoff. The leftover water soaks into the ground and fills the openings in the soil and trickles into cracks and spaces in layers of rock. Just like running water on the surface, groundwater also affects the shape of the land. Groundwater can cause erosion through a process called chemical weathering. This process is the process when water sinks into the ground, combines with carbon dioxide, and the becomes a weak acid, called carbonic acid. Carbonic acid can break down limestone. Groundwater that contains carbonic acid flows into any cracks in the limestone. After that, some of the limestone changes chemically and is carried away in the solution of water. This process can gradually hollow out pockets in the rock. Then, over time, these pockets can develop into large underground holes, called caves or caverns.
Cave FormationsThe action of carbonic acid on limestone can also result in deposition. Inside limestone caves, deposits called stalactites and stalagmites often form. Stalactite is a deposit that hangs like an icicle from the roof of a cave. A stalagmite is a cone shaped object coming up from the cave floor that results from slow dripping. These deposits happen when water containing carbonic acid and calcium from limestone drips from a cave's roof and carbonic acid id released from the solution. This leave's behind a deposit of calcite.
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Karst TopographyKarst topography is a type of landscape named after a region in Eastern Europe. Karst topography develops in rainy regions where there is a layer of limestone near the surface., and groundwater erosion can significantly change the shape of the land. Streams are rare in these areas because water easily sinks down into the weathered limestone. In contrary, deep valleys and caverns are very common. If the roof of a cave collapses because of the underlying limestone, the result is a depression called a sinkhole. In the United States, regions of karst topography are found in Florida, Texas, and many other states.
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