EARTH SCIENCE
GROUNDWATER
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Groundwater is often mildly acidic as it contains a weak solution of carbonic acid.
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The acidic nature of groundwater will dissolve the calcite in limestone.
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Caverns are formed by dissolving rock beneath the Earth’s surface.
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Plate subduction can create caverns as one plate dives under another.
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Detailed explanation-1: -Rainwater picks up carbon dioxide from the air and as it percolates through the soil, which turns into a weak acid. This slowly dissolves out the limestone along the joints, bedding planes and fractures, some of which become enlarged enough to form caves.
Detailed explanation-2: -Some of the precipitation that falls onto the land infiltrates into the ground to become groundwater. If the water meets the water table (below which the soil is saturated), it can move both vertically and horizontally.
Detailed explanation-3: -Groundwater erosion is the process by which groundwater erodes part of the bedrock as it passes through. This is primarily due to carbonic acid in the groundwater, which forms when rainwater picks up carbon dioxide in the atmosphere as it falls.
Detailed explanation-4: -Carbonate rocks such as limestone, composed mostly of the mineral calcite (CaCO3) are very susceptible to dissolution by groundwater during the process of chemical weathering. Such dissolution can result in systems of caves and sinkholes.