fenster

geology

Also known as: window

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June 26, 2026

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In geology, a fenster is an opening in overthrust rock that exposes the underlying rock. This geological feature is also called a "window". Fenster typically form when erosion cuts into a large body of rock, known as a nappe, which has been moved from its original position by faulting or folding. This process can expose younger, underlying rock that is completely surrounded by the older, overthrust rock. These openings are often found in topographic basins or deep valleys. The term "fenster" originates from the German word for window.12

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nappe
…this patch is called a fenster, or window. Fensters generally occur in topographic basins or deep, V-shaped valleys. Elsewhere, an eroded, isolated remnant of the older rock or nappe may be completely surrounded by the younger, underlying rock; this is known as a klippe, or thrust outlier. Mythen Peak in…
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…this patch is called a fenster, or window. Fensters generally occur in topographic basins or deep, V-shaped valleys. Elsewhere, an eroded, isolated remnant of the older rock or nappe may be completely surrounded by the younger, underlying rock; this is known as a klippe, or thrust outlier. Mythen Peak in…
Read More