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Learn how water processes change the Earth's surface, including acid rain, groundwater erosion, and cave formations resulting from water mixing with CO2. Explore karst topography, sinkholes, stalactites, and stalagmites.
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Water Erosion: How do processes involving water change Earth’s surface? Part 3
What results from water in the atmosphere mixing with CO2(carbon dioxide) ? Acid Rain
Precipitation and Groundwater Water in the atmosphere combines with carbon dioxide (CO2) to form a weak acid known as carbonic acid. Another term for this is “acid rain”. When the precipitation falls on Earth’s surface, the water that does not evaporate back into the atmosphere or runoff the surface can sink into the ground. Water that soaks into the ground is known as groundwater, and becomes part of the groundwater system.
Groundwater Weathering Groundwater weathers rocks which contains CaCO4 (calcium carbonate). Examples of this type of rock are limestone, marble, and chalk). The groundwater (weak carbonic acid) dissolves those rocks in the process of chemicalweathering.
Groundwater Erosion As the rock dissolves, it goes into solution with the groundwater, and flows along with the groundwater. This underground movement of chemicallyweathered rock is known as groundwater erosion. This process will gradually hollow out pockets in the rock. Over time, the pockets develop into large holes called caves or caverns.
Cave Formations: How do they form?
Groundwater Deposition Once the cave or cavern is established: the groundwater solution can drip from the ceiling to the floor. Evaporation occurs as the solution slowly drips from the ceiling. Evaporation also occurs when the solution has fallen to the floor. As the water evaporates: the minerals (such as calcite) in the solution will be left behind (or deposited) hardening on the ceiling and floor of the cave or cavern causing cave formations.
Cave Formations: What are the features found in a cave?
Cave Formations What are stalactites? Calcite deposits that hang from the cave’s roof likeicicles What are stalagmites? Cone-shaped calcite deposits that build up from the cave floor
Ellison’s Cave in Walker County, Georgia http://www.georgiaencyclopedia.org/nge/Article.jsp?id=h-2130 http://www.georgiaencyclopedia.org/nge/Article.jsp?id=h-2130
Karst Topography: What happens when land rich in limestone is weathered and eroded by groundwater?
Sinkholes Sinkholes are: depressions in the ground. Sinkholes are caused when : the roof of a cave or cavern collapses because of the erosion of the underlying rock (limestone) with the result being the depression. Sinkhole Formation Animation
Karst Topography A Karst Topography is A type of landscape Karst Topography is created in regions where : a layer of limestone near the surface forms deep valleys, caves, caverns, and sinkholes.
Karst Topography http://www.virginiacaves.org/lok/ccvup56.jpg
Karst Topography http://4.bp.blogspot.com/_JRp7TJWTx4A/S8Z8B2hEMVI/AAAAAAAAAVk/h0MJosarOQ0/s320/karst_cave.jpg