Unloading joints in granodiorite, Yosemite National Park.
The near-horizontal fractures in this photo are "unloading joints" that form by upwards expansion of the bedrock as overlying material is stripped away by erosion. In this way, a landscape tends to perpetuate itself because the new fractures, which greatly influence subsequent erosion, run roughly parallel to the land surface. They typically form in homogeneous rock, such as granite.

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