Two new geologic maps available from CGS
October 9, 2017 - CGS is pleased to announce the release of two new geologic maps.
The first release, Preliminary Geologic Map of the Cedarville 30’ × 60’ Quadrangle, Modoc County, California, by Thomas L.T. Grose, Anne E. Egger, and Matt D. O’Neal, is available as a
downloadable PDF file with a companion pamphlet. The Cedarville Quadrangle is the fourth and final map in a series of adjacent geologic maps, including (from south to north): Susanville, Eagle Lake, Alturas, and Cedarville. The Cedarville Quadrangle spans portions of the Basin and Range and Modoc Plateau geomorphic provinces, and is largely underlain by Tertiary age volcanic rocks and associated volcaniclastic sedimentary rocks. Major geologic features of the area include the Devils Garden Plateau, a region of horizontal strata with little structural relief, the Goose Lake Valley graben, the north-south – trending horst of the Warner Range and the Surprise Valley half graben. The Surprise Valley fault between the Warner Range and Surprise Valley is characterized by fresh scarps in modern alluvium associated with Holocene activity.
The second release, Geology of the Independence Lake and Hobart Mills 7.5’ Quadrangles, Sierra and Nevada Counties, California (Map Sheet 63), by Arthur Gibbs Sylvester and Gary L. Raines, is a
printed product available from CGS Publications for just $30 each. This new map covers a portion of the northern Sierra Nevada, just north of Donner Lake and the town of Truckee. The map represents the work of the authors with contributions from 32 students and graduate teaching assistants. Cretaceous hornblende-biotite granodiorite, Miocene and Pliocene andesitic lava flows and volcaniclastic deposits are the principal rock types in the map region. Large areas are covered with Pleistocene glacial drift related to at least three stages of glaciation. Two major fault zones strike northwestward through the region. The faults represent the westward incursion of Basin and Range faulting into this part of the northeastern Sierra Nevada.
CGS releases ten proposed new and revised Preliminary Seismic Hazard Zone maps
August 17, 2017 - Click here to view and download the Preliminary Seismic Hazard Zone maps and their associated Evaluation Reports. Areas covered are within Contra Costa, Riverside and San Mateo counties and affect the cities of Antioch, Belmont, Brentwood, Burlingame, Foster City, Hillsborough, Menlo Park, Murrieta, Oakley, Redwood City, San Carlos, San Mateo, Temecula and Wildomar.
California ranks sixth among the states in Non-Fuel Mineral Production in 2015
July 28, 2017 - In 2015, California non-fuel mineral production accounted for approximately 4.2 % of the United States total. There were 717 active mines in the state and the total market value of production was $3.6 billion.
CGS announces Web Services for Alquist-Priolo Earthquake Fault and Seismic Hazard Mapping Zones
July 27, 2017 - The CGS Seismic Hazards Program is pleased to announce it has released all of its regulatory hazard zone data as web-based services.
CGS releases four proposed new and revised Preliminary Alquist-Priolo Earthquake Fault Zone maps
July 13, 2017 - Click here to view or download the proposed revised maps and their associated Fault Evaluation reports. Areas covered are within Los Angeles and Napa Counties and affect the cities of Beverly Hills, Culver City, Los Angeles, Napa, Santa Monica, Vallejo, and West Hollywood.
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