Blueschist - Menlo Park, California
Posted by: Groundspeak Premium Member Volcanoguy
N 37° 27.312 W 122° 10.214
10S E 573387 N 4145694
Blueschist block at the USGS Campus in Menlo Park, California.
Waymark Code: WMADGZ
Location: California, United States
Date Posted: 12/31/2010
Published By:Groundspeak Regular Member lenron
Views: 2

This blueschist block is one example of a series of large blocks of rocks from various locations, which are on display around the USGS Campus in Menlo Park. There is a self-guided tour of the campus available at the visitor center.
Text of Sign: “This seven ton monolith of contorted and lineated blueschist from the Franciscan Complex was collected from the Tiburan Peninsula five miles north of San Francisco. Similar blueschist blocks from that locality have been dated at about 160 million years. The rock contains galaucophane, which imparts the blue color, white mica, epidote, sphene, and 2 mm-diameter crystals of red garnet. The minerals comprising blueschist crystallize under rather unique conditions of metamorphism which are: high pressure, from burial at depths greater than about 18 km, and relatively low temperatures near 400° C.”

Type of Display: Geological

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Volcanoguy visited Blueschist - Menlo Park, California 12/15/2010 Volcanoguy visited it