Differential weathering and differential erosion are often, jokingly, the default explanations for odd-looking rocks or geologic scenery.  But they are important, real-life processes.  Differential weathering and differential erosion refer to the result of hard, resistant rocks & minerals weathering and eroding more slowly that softer, less-resistant rocks & minerals.  These processes explain the unique scenery at, for example, Arches National Park in Utah.


The rock shown below is an intrusive igneous rock (gabbro?) with two intersecting granite dikes.  The dikes noticeably project from the rock surface.  The dark host rock has weathered & eroded at a faster rate than the granite dikes.


Differential weathering and erosion on a dark-colored intrusive igneous rock (gabbro?) having intersecting, pinkish-colored granite dikes that project from the rock surface (public display, Field Museum of Natural History, Chicago, Illinois, USA).



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