Monumental Questions - What's so Amazing about Molok Luyuk's Geology?

Nate Lillge • October 25, 2023

Molok Luyuk Geology

Molok Luyuk is a geologically unique area that exhibits 60 to 100 million years of history within an unusually small area. Its dramatic plate tectonic geology gives rise to extraordinary biodiversity and determines its human history. Geologists and miners have flocked to the area, the former to gain scientific understanding, the latter for mercury and gold. It has been called “perhaps the most accessible location” to see the unique geology of the Berryessa Snow Mountain National Monument.


On Molok Luyuk, one will experience the Coast Range Ophiolite, which dates from the middle to late Jurassic Age. Nearby are the Coast Range Thrust Fault and visible contacts between the North American Plate and the ancient Farallon Plate. Serpentinite, California’s state rock and the rock that produces much of the area’s unique soils and biodiversity, is visible throughout Molok Luyuk. As a result, the hydrology of the area is unique, with much-studied geothermal, mineral, carbonated, and freshwater springs that dot the area. Paleontological studies of fossils in the region not only help to date the area, but also show how the tectonic plates have moved, including the displacement along the Bartlett Springs Fault Zone. A walk across Molok Luyuk is a walk through 100 million years of history.


Molok Luyuk is thus a wonderful mashup of the millions of years of geological processes that led to what is now California. When exploring this ridge, even non-geologists can easily see the different types of bedrock and the life that has evolved on each. Plants growing on serpentine soil have evolved to have (generally) small, waxy leaves, and are often shorter than plants on non-serpentine soil. Different plant communities are easy to see on Molok Luyuk and faults can often be found at or near the borders of these communities.


-Nate Lillge (nlillge@tuleyome.org)


Tuleyome Adventures and Engagement Director


Certified California Naturalist

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