Roadside Geology of Northern and Central California (Roadside Geology Series)
Language: English
Pages: 384
ISBN: 0878426701
Format: PDF / Kindle (mobi) / ePub
California s geology makes headlines when faults shift, volcanoes puff steam, and coastal bluffs fall into the sea. The latest edition of this popular book explores the state s recent rumblings and tremulous past with the aid of full color illustrations. Spectacular photographs showcase multihued rock, from red chert and green serpentinite to blue schist and gray granite. The color geologic road maps, based on the 2010 Geologic Map of California, are detailed and easy to read. The geologic information, particularly for the Klamath Mountains, Modoc Plateau, and northern Sierra Nevada, has been updated to reflect the more recent geologic understanding of these complex areas. For your next road trip, replace your tattered, dog-eared copy of the old edition with this gorgeous new volume.
River 1 49 Big Bend fault zone Flea Valley Creek \ Geologic section approximately along the line of California 70 between Oroville and Greenville, across rocks of the Western Jurassic, Calaveras, and Shoo Fly terranes. Cresta CZQ) SIERRA NEVADA Big Slab ofMantle Just east of Rich Bar, the road passes nearly continuous big cuts in dark green serpentinites and black peridotites. They are in the Feather River peridotite belt, a slab of mantle rock that somehow found its way into the
the Western Jurassic belt, which lies on the South Fork Mountain fault. Its rocks are mainly peridotite, partly altered to serpentinite. The several masses of gabbro crystallized in the base of the oceanic crust. The slates of the Galice formation were deposited on the Josephine ophiolite when it was still part of the ocean floor. They also belong to the Western Jurassic belt. WESTERN J U RAS S I C B E LT WESTERN PALEOZOIC AND TRIASSIC BELT OREGON CALIFORNIA .}{ 1 big roadcuts in black
through an oceanic trench reaches a trench depth of about 50 miles, its temperature rises to about 550 degrees centigrade. At that point, the serpentinite loses its water and reverts to peridotite. Under those conditions, the water is technically a supercritical fluid, neither water nor steam in the ordinary sense of the terms. The red hot fluid rises into the rocks above, melting them to make magmas. The magmas feed the volcanic chain that invariably rises parallel to an oceanic trench, 50 to
along the eastern rim of the Cotati Valley are the eroded remains of the Sonoma volcanic pile. It consists mostly of pale volcanic ash that erupted while the valley was a bay. Rhyolite ash flows overwhelmed and buried redwood forests, now preserved as petrified logs and stumps. Together, the rocks and fossils conjure a picture of a broad saltwater bay enclosed on its north and south sides within hills eroded in Franciscan rocks, and nestled beneath high volcanoes to the east. A dark cloak of
.-·�.·��\ ·:::-�::� Lakepo'rt':• �.;.-,.. �·.-.·.-··• ·_ �. ·.. t;/)\:. I · ,, � ·, . :� ·>:�·�·/�:· , --:, :: ---::- � ·.�·- ·. · . .! //�·: : ·�� ·: roadcuts in brownish ribbon chert 0 miles 10 20 area of low earthquake velocity, magma as shallow as 4 miles below the surface Sulphur Bank flow Rocks along California 20 between Calpella and Williams. Coast Range ophiolite @) 1 59 COAST RANGE E W S A C R A M E N T O VA L L E Y Coast Range lite Geologic section across the