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Etchplain
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<p>An etchplain is a plain where the <a href="/facts/Bedrock/mn9WCgtX">bedrock</a> has been subject to considerable "etching" or <a href="/facts/Weathering/uSYGlv0H">subsurface weathering</a>. Etchplanation is the process forming etchplains. Contrary to what the name might suggest, etchplains are seldom completely flat and usually display some relief, as weathering of the bedrock does not advance uniformly. This means that weathering is unrelated to the flatness which might be derivative of various other processes of <a href="/facts/Planation_surface/XLmQHfd3">planation</a> including <a href="/facts/Peneplain/XFFH9lm1">peneplanation</a> and <a href="/facts/Pediplain/654rDXoj">pediplanation</a>. Erosion of etchplains can result in the exposure of <a href="/facts/Inselberg/RElGgtxh">inselbergs</a> such as <a href="/facts/Bornhardt/dlvrlDMj">bornhardt</a> and <a href="/facts/Tor_(rock_formation)/2jMCnKbR">tors</a>. Generally the topography exposed at a stripped etchplain, that is an etch surface, after erosion of <a href="/facts/Regolith/EdXuHK56">regolith</a> is one with many irregularities as result of <a href="/facts/Structural_geology/e6tGSc6K">structurally defined</a> areas of rock strength. </p><p>A distinction can be made between etchplains and etch surfaces as the latter may or may not be flat and can represent the landform arising from the stripping of an etchplain. </p><p>As climate changes, arid and semi-arid periods of pediplanation may alternate with more humid periods of etchplanation resulting in the formation of flattish surfaces (<a href="/facts/Peneplain/XFFH9lm1">peneplains</a>) of mixed origin (polygenetic). </p><p>During wet seasons <a href="/facts/Deep_weathering/uSYGlv0H">deep weathering</a> is more pronounced producing regolith which is then stripped away by erosion during subsequent dry seasons. The rate of stripping must exceed that of regolith production by deep weathering, otherwise deep-seated basal surfaces would not be revealed. </p><p>The <a href="/facts/African_Surface/1JlWamrs">African Surface</a> formed 70–40 million years ago is an example of an etchplain. </p>