“A geologist is a fault finder.” – Anonymous
“Beneath all the wealth of detail in a geological map lies an elegant, orderly simplicity.” – Tuzo Wilson
LAKE COUNTY, Calif. – Taking a walk almost any place in Lake County can be like viewing a museum in the soil.
The hills, valleys and streams contain a wealth of geologic diversity. In fact, our California Coast Ranges are world-famous for their impressive geologic features.
Here in our own chapter of the geologic history book we can “read” the past's violent volcanics in 2-million-year-old igneous rock features such as andesite – that red-hued rock.
We can walk amongst a myriad of sedimentary stratigraphies, like sandstone, shale, mudstone and copious conglomerates.
If those tilting, lumps and deposits could talk, they would divulge the secrets of their many minerals and metals.
Gold has been mined here in Lake County, most recently at the McLaughlin Gold Mine in Lower Lake, which is now a nature reserve.
The gold found there was usually microscopic in nature, however, nuggets were unearthed from time to time.
Gold is typically found in quartz, gravel and some sulphurets, such as are produced by hot springs.
Our county has produced everything from silver and iron to quicksilver (mercury) and borax.
To explain the geology of Lake County, Dr. Harry Lyons explained in a recent statement for the Lake County Library's “Know Lake County series, “We live in a clutter of marine rocks, delivered from the Pacific by forces beautifully described by a theory called plate tectonics. The position and composition of the rocks, for millions of years, have formed and subsidized the ecosystem of the Clear Lake Basin. Our dynamic landscape, powered by the San Andreas Fault System, has led to the development of our famous eutrophic lake, a favorite of biologists worldwide.”
Lake County's hills and streams house an abundance of shiny serpentine, California's state rock.
Serpentine's color ranges from green to black, and is speckled with both dark and light features. It is also abundant in the Sierra Nevada foothills and the Klamath Mountains.
According to the California Geologic Survey publications, serpentine can be metamorphic as well as igneous, containing peridotite straight from earth's mantle, which is below earth's crust.
During a Coyote Valley Elementary School field trip recently, we had the honor of taking a mini geology class on Putah Creek with geologist Dean Enderlin. He is a walking geology encyclopedia.
According to Enderlin, you won't be able to find any dinosaur bones or fossils here in Lake County, because during that time – more than 150 million years ago, in the Jurassic Period – all of Lake County was submerged under the ocean.
If you look carefully, perhaps in a chunk of chert rock plucked from a creek, you will see fossils of shells.
Kathleen Scavone, M.A., is an educator, potter, writer and author of “Anderson Marsh State Historic Park: A Walking History, Prehistory, Flora, and Fauna Tour of a California State Park” and “Native Americans of Lake County.” She also writes for NASA and JPL as one of their “Solar System Ambassadors.” She was selected “Lake County Teacher of the Year, 1998-99” by the Lake County Office of Education, and chosen as one of 10 state finalists the same year by the California Department of Education.
The Living Landscape: Geology of Lake County
- Kathleen Scavone
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