Posted by: frank Post Reply
California has in common with western Washington the Franciscan terraine which begins just north of the Golden Gate and is the dominant rock west of Napa valley until the Oregon border.This is jade country. The Franciscan came north as an island arc chain from the far south of Mexico and smashed into the things that had smashed into the continent previously. RG Coleman was a Stanford professor of geology who was the state jade geology expert. He wrote non academic articles also. A very good paper on the Clear lake jade belt was still on the internet recently but has been a bit hard to find the last 10 years.
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