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Geology of Vasquez Rocks
Researched and Compiled by Sarah Brewer

Aerial view of the majority of Vasquez Rocks Natural Area Park, with State Route 14 Freeway visible in the lower right and
Escondido Canyon Road (the road used to access the park) visible in the upper left. Note clearly visible sandstone layers which
form the unique and dramatic landscape. Image ©Google Maps, 2016.

The Rocks are located in what is known as the Soledad Basin, which sits cradled to the south of
the smaller Sierra Pelona Mountains, and to the west and north of the more well-known, larger San
Gabriel Mountains. Soledad Canyon runs to the south of the park, Mint Canyon runs to the north, and
Agua Dulce Canyon runs north to south right through the Vasquez Rocks area.

The distinctive formations in the Vasquez Rocks area were actually formed through a relatively
simple process, and the clues to its creation are still visible all around. Over the course of the past 25
million years (the most commonly agreed-upon age by geologists), vast amounts of sediment (sand, soil,
rocks, and organic materials) were brought downward into the Soledad Basin by events such as rains,
flooding, landslides, wind, and earthquakes from the surrounding San Gabriel and Sierra Pelona
Mountains. As these materials were deposited on the basin’s floor, they would settle flat on the ground
surface, and as years passed, new deposits covered the older ones, eventually placing them under
tremendous amounts of pressure. With this pressure, the deeper layers became solidified, turning into
what we know as sandstone.
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