​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Welcome to the California Geological Survey

​​​​​​​​​​​​THE CALIFORNIA GEOLOGICAL SURVEY is one of the oldest geological surveys in the United States, having been established in 1860. We map and analyze data on the state's diverse geologic environment, earthquakes, and other geologic hazards and mineral resources to provide critical information to protect life, property, commerce, and the environment from natural hazards. The California Geological Survey is regarded as the primary source of geologic information used for decision-making by California's government agencies, its businesses, and the public.

–“A​LTIORA PETIMUS”​ ​(We Reach Higher​​)

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CGS​ ​​​News​

​​​Map Sheet 52 (2018 update): Aggregate Sustainability in California - ​Fifty-Year Aggregate Demand Compared to Permitted Aggregate Reserves

Posted: 7/16/2018 2:00 PM

​​​​​The building and paving industries in California consume large quantities of aggregate, and future demand for this commodity is expected to increase throughout California. Aggregate materials are essential to modern society, both to maintain the existing infrastructure and to provide for new construction. Map Sheet 52 is a statewide overview of projected future aggregate needs and currently permitted reserves. The purpose of the map is to compare projected aggregate demand for the next 50 years with currently permitted aggregate reserves in various regions of the state. The map also shows the projected years of permitted reserves remaining and highlights regions where less than 10 years of permitted aggregate supply remain. Map Sheet 52 was originally published in 2002 and subsequently updated in 2006 and 2012; this 2018 release is an update of the version published in 2012.

View/download the full release s​tatement (PDF document) - The release statement provides background information and a summary of findings, as well as pricing for printed versions of the map.

Links to the Report and Map

View/download ​​​'Map Sheet 52 (2018 update): Aggregate Sustainability in California - ​Fifty-Year Aggregate Demand Compared to Permitted Aggregate Reserves​' ​(4 MB PDF document)

View/download the Report (PDF document) - The report provides detailed information​​, and is divided into three parts:

  • ​Part I - provides data sources and methods used to derive the information presented.
  • Part II - compares the updated 2018 Map Sheet 52 to the prior (2012) map.
  • Part III - provides an overview of construction aggregate.

​​Landslides, Geomorphology, and Geology of the Owl Creek and Iaqua Buttes 7.5’ Quadrangles​, Humboldt County, California​

Posted: 7/6/2018 2:00 PM

​​​​​​​CGS is pleased to announce the release of two new geologic maps: Landslides, Geomorphology, and Geology of the Owl Creek 7.5’ Quadrangle, Humboldt County, California, and Landslides, Geomorphology, and Geology of the Iaqua Buttes 7.5’ Quadrangle, Humboldt County, California, both by James N. Falls, Gerald J. Marshall, Don R. Braun, and Shannon M.B. Utley. Both maps are available as downloadable PDF files.

The Owl Creek Quadrangle straddles the boundary of the Coastal and Central Belt portions of the Franciscan complex, and is underlain by three distinct northwest trending fault-bounded packages of sedimentary rocks. From west to east, late Pleistocene- to Miocene-aged marine and non-marine overlap deposits of the Wildcat Group are faulted against rhythmically interbedded Eocene- to Paleocene-aged sediments of the Yager Terrane (Coastal Belt) along the Little Salmon fault. The Yager Terrane rocks are faulted against Paleogene- to late Cretaceous- aged tectonic mélange of the Central Belt along the Freshwater fault. The faults are related to initial emplacement of Franciscan complex rocks along the western edge of North America, and more recent faulting related to northwest migration of the Mendocino Triple Junction. Age of faulting within the Owl Creek Quadrangle may be late Quaternary, however, faulting on the Little Salmon fault northwest in the adjacent Hydesville Quadrangle is considered Holocene based on relatively fresh scarps and topographic lineaments observed in recent alluvium.

The Iaqua Buttes Quadrangle straddles the boundary of the Coastal and Central Belt of the Franciscan complex, and is underlain by two distinct northwest trending fault-bounded packages of sedimentary rocks. From west to east, rhythmically interbedded and sheared Eocene- to Paleocene-aged sediments of the Yager Terrane (Coastal Belt) are faulted against Paleogene​- to late Cretaceous-aged tectonic mélange of the Central Belt along the Freshwater Fault. The Freshwater fault is related to initial emplacement of Franciscan complex rocks along the western edge of North America and shows evidence of early Quaternary movement.

These are the first two maps in a series of adjacent geologic maps that will include Owl Creek, Iaqua Buttes, Mad River Buttes, and Yager Junction.​

Download the map, 'Landslides, Geomorphology, and Geology of the Owl Creek 7.5’ Quadrangle, Humboldt County, California'

​Download the map, 'Landslides, Geomorphology, and Geology of the Iaqua Buttes 7.5’ Quadrangle, Humboldt County, California'​

​​California’s Non-Fuel Mineral Production in 2016​

Posted: 6/12/2018 8:00 AM

​​The California Geological Survey provides an annual summary of the state’s mineral production exclusive of oil, gas, geothermal, and coal. In 2016, California ranked fourth among the states in non-fuel mineral production, accounting for approximately 4.5 % of the United States total. There were 663 active mines in the state producing non-fuel minerals during 2016. The total market value of production was $3.4 billion. In terms of value, the top five non-fuel minerals produced in 2016 were construction sand and gravel, portland cement, boron minerals, crushed stone, and soda ash.

Download the report, 'California Non-Fuel Minerals 2016'

Follow this link to learn more about California’s Non-Fuel Mineral Production

Earthquake Hazards Search is easier with EQ Zapp​

California Geological Survey unveils web application to help public locate Earthquake Hazard Zones

Posted: 3/21/2018 10:00 AM

​​​​​​​​​​The California Earthquake Hazards Zone Application is an online map that allows anyone with a computer, tablet or smartphone to conveniently check whether a property is in an earthquake hazard zone. With this tool, you can type in an address or use the location capability of your computer or mobile device to determine whether a pro​perty lies within any of CGS’s mapped earthquake hazard zones. It will also tell you if CGS has not yet evaluated the hazards in that area.

Follow this link to explore the California Earthquake Hazards Zone Application​​

​​​Speci​al Report 240 - Update of Mineral Land Classification: Portland Cement Concrete-Grade Aggregate in the Western San Diego County Production-Consumption Region of California​

Posted: 2/16/2018 8:00 AM

​​​​​​California's Surface Mining and Reclamation Act of 1975 (SMARA) requires the State Geologist to classify land into Mineral Resource Zones (MRZs), based on the known or inferred mineral resource potential of that land. The primary goal of mineral land classification is to help ensure, through appropriate local lead agency policies and procedures, that mineral resources will be available when needed and do not become inaccessible because of inadequate information during the land-use decision‑making process.​

This report is the third in a series of regional mineral land classification reports for portland cement concrete (PCC)-grade aggregate for the Western San Diego County Production-Consumption Region (P-C Region).  It updates the mineral land classification of the region, reevaluates the region's PCC-grade aggregate resources, and includes an updated 50‑year projection of construction aggregate demand for the P-C Region through the year 2065.

Download the full release statement​

Links to the Report and Maps

​Download Special Report 240 (SR 240) - 2017 Update of Mineral Land Classification: Portland Cement Concrete-Grade Aggregate in the Western San Diego County Production-Consumption Region, California

Download Plate 1 - Updated (2017) Mineral Land Classification Map for Western San Diego County

Download Plate 2A - Updated (2017) Aggregate Resource Sector Map for Western San Diego County​ - Northern Part

Download Plate 2B - Updated (2107) Aggregate Resource Sector Map for Western San Diego County​​​ - Southern Part

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