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Alves pit, Bay Point (West Pittsburg), Contra Costa Co., California, USA

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Latitude & Longitude (WGS84): 38° 1' 12'' North , 121° 57' 10'' West
Latitude & Longitude (decimal): 38.02000,-121.95278
Köppen climate type:Csa : Hot-summer Mediterranean climate

A clay & stone (crushed/broken) deposit/pit operation located in the NE¼SE¼ sec. 15, T2N, R1W, MDM, 1.3 km (0.8 mile) SE of Bay Point. Owned & operated by Eugene G. Alves, California (1990). MRDS database stated accuracy for this location is 100 meters.

Local rocks include Plio-Pleistocene and Pliocene loosely consolidated deposits.

Workings include surface openings comprised of 2 pits.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

 No mineral species recorded.

Rock Types Recorded

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Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

Holocene - Pleistocene
0 - 2.588 Ma

ID: 2540961
Surficial deposits, undivided

Age: Pleistocene (0 - 2.588 Ma)

Description: For more detailed reports of surficial deposits, see Helley and others (1979), Atwater (1982), Herd (1978 a, b), and Borchardt and Seelig (1991).

Reference: Graymer, R.W., D.L. Jones, E.E. Brabb. Preliminary geologic map emphasizing bedrock formations in Contra Costa County, California. U.S. Geological Survey Open-File Report 94-622. [86]

Pleistocene - Miocene
0.0117 - 23.03 Ma

ID: 2937097
Plio-Pleistocene and Pliocene loosely consolidated deposits

Age: Cenozoic (0.0117 - 23.03 Ma)

Stratigraphic Name: Arroyo Seco Gravel; Cache Formation; Carlotta Formation; China Hat Gravel; China Ranch Beds; Coso Formation; Funeral Fanglomerate (part); Furnace Creek Formation; Glen Ellen Formation; Irvington Gravels; Kern River Formation; Laguna Formation; Livermore Gravel; McKittrick Formation; North Merced Gravel; Nova Formation; Packwood Gravels; Paso Robles Formation; Red Bluff Formation; Ricardo Formation; San Benito Gravels; Santa Clara Formation; Saugus Formation; Tehachapi Formation; Tulare Formation; Turlock Lake Formation; Alturas Formation; Anaverde Formation; Canebrake Conglomerate; Chanac Formation; Crowder Formation; Duarte Conglomerate; Esmeralda Formation; Etchegoin Formation; Green Valley Formation; Hathaway Formation; Horned Toad Formation; Hungry Valley Formation; Lockwood Clay; Mecca Formation; Meeke Mine Formation; Mehrten Formation; Morales Formation; Mount Eden Formation; Mulholland Formation; Neroly Formation; Orinda Formation; Oro Loma Formation; Painted Hill Formation; Palm Spring Formation; Panorama Hills Formation; Peace Valley Formation; Petaluma Formation; Potato Sandstone; Purisima Formation; Quatal Formation; Ricardo Formation (part); Ridge Route Formation; Santa Ana Sandstone; San Timoteo Formation; Siesta Formation; Tassajero Formation; Tehama Formation; Tropico Group; Wolfskill Formation

Description: Pliocene and/or Pleistocene sandstone, shale, and gravel deposits; in part Miocene.

Lithology: Major:{sandstone,conglomerate}, Minor:{siltstone,mudstone}, Incidental:{limestone, evaporite, coal, sedimentary breccia}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

2.588 - 5.333 Ma

ID: 2590592
Tehama Formation

Age: Pliocene (2.588 - 5.333 Ma)

Description: In Pittsburg assemblage, poorly consolidated, nonmarine, gray to maroon siltstone, sandstone, tuff, and conglomerate. This unit was correlated with the Tehama Formation in the Vacaville Assemblage based on the presence of tuff correlated with the Putah Tuff member (Sims and Sarna-Wojcicki, 1975). In Vacaville assemblage, white quartz arenite, tuffaceous sandstone, siltstone, and pebble to cobble conglomerate. This unit also contains beds of white ash tuff and pink tuff breccia. In the northern part of the map area, the Tehama Formation includes Putah Tuff member (Tptt) near the base. Putah Tuff member is water-lain tuff and tuffaceous and volcaniclastic sedimentary rocks. This member has yielded a radiometric age of 3.3 ± 0.1 Ma (K/Ar, Miller, 1966). This member was correlated with the Nomlaki Tuff Member of the Tehama Formation north of the map area, which is similar in age, but chemical analysis has shown the tuffs to be distinct (Miller, 1966; Sarna-Wojcicki, 1976)

Comments: Pittsburg Assemblage; Vacaville Assemblage

Reference: Graymer, R.W., D.L. Jones, E.E. Brabb. Geologic Map and Map Database of Northeastern San Francisco Bay Region, California. U.S. Geological Survey Miscellaneous Field Studies Map MF-2403. [92]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


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California Journal of Mines and Geology (1958): 54(4): 575, Pl. 5.
California Division of Mines and Geology (1990), Mines and mineral producers active in California (1988-89), California Department of Conservation, Division of Mines and Geology, Special Publication 103.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10029574 & 10162857.
U.S. Bureau of Mines Minerals Availability System/Mineral Industry Location System (MAS/MILS): file #0060130091.

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