Flag Hill, made up of fossiliferous sandstone of the Briones Formation, overlooks the Sunol Regional Wilderness. Photos by Andrew Alden
Melange country, with the Mission Hills beyond the Calaveras fault. Note the radio towers of Monument and Mission Peaks.
Sunol Regional Wilderness is east of the Calaveras fault. LY, Little Yosemite; FH, Flag Hill; P, southern parking lot. Tan colors are young sandstones of the Briones Formation and related units; green is Great Valley Sequence sandstone of Cretaceous age; blues and purples are Franciscan rocks including melange, graywacke (sandstone) and serpentinite.
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Upper reaches of the “W” Tree Rock Scramble.
Beneath a thin veneer of stream gravel lies solid bedrock: a stream-cut platform.