| Merced Formation | |
|---|---|
| Stratigraphic range: Pliocene, Neogene Period | |
| Type | Geologic formation |
| Underlies | Colma Formation (California) |
| Overlies | Bedrock (California) |
| Lithology | |
| Primary | sedimentary rock (California) |
| Location | |
| Region | San Francisco Bay Area of California, Oregon, Washington (state) |
| Country | United States |
| Type section | |
| Named for | Lake Merced |
The Merced Formation is a geologic formation in California, and also in Oregon and Washington state. It is named for Lake Merced, a natural lake on the western San Francisco coastline.[ citation needed ] The California portion is composed of a variety of sediments deposited on the coast of the San Francisco Bay Area in a small basin, which was split into two halves by the San Andreas Fault.
In the coastal San Francisco Bay Area of California the Merced Formation was deposited in a small sedimentary basin that formed along the San Andreas Fault during the last two million years during the Pliocene age of the Neogene period, in the Cenozoic Era. [1] [2] It is composed of sediments deposited in a variety of coastal settings and depths, including coastal shelf, nearshore, and even non-marine environments. [1] Younger layers of the formation show a general shallowing trend in the water, but superimposed on this, there is a periodic small-scale repetition of slightly deeper and shallower environments, resulting from sea level oscillations caused by climate change. [1] The repeated occurrence of shallow-water deposits in the sequence indicates that the formation was deposited in a subsiding sea. [1] Marine deposits in the formation are varied. [1] One section includes a layer of dark, bioturbated sand, a layer of parallel laminated and burrowed sand and silt, and a layer of cross-bedded gravel and pebbly sand. [1]
The fault cut the basin into two pieces and moved the pieces apart. It is found on the east side of the fault in western San Francisco and northern San Mateo County. On the west side of the fault it was carried 20 miles (32 km) north to the Bolinas headlands of western Marin County. [2]
Fort Funston is on a bluff made up of exposed sedimentary rocks of the Merced Formation, in San Francisco within the NPS Golden Gate National Recreation Area. [2]
The Los Angeles Basin is a sedimentary basin located in Southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the Transverse Ranges. The present basin is a coastal lowland area, whose floor is marked by elongate low ridges and groups of hills that is located on the edge of the Pacific Plate. The Los Angeles Basin, along with the Santa Barbara Channel, the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, lies within the greater Southern California region. The majority of the jurisdictional land area of the city of Los Angeles physically lies within this basin.
Seal Rock is a group of small rock formation islands in the Lands End area of the Outer Richmond District in western San Francisco, California. They are located just offshore in the Pacific Ocean, at the north end of the Ocean Beach, near the Cliff House and Sutro Baths ruins.
The Coyote Mountains are a small mountain range in San Diego and Imperial Counties in southern California. The Coyotes form a narrow ESE trending 2 mi (3.2 km) wide range with a length of about 12 mi (19 km). The southeast end turns and forms a 2 mi (3.2 km) north trending "hook". The highest point is Carrizo Mountain on the northeast end with an elevation of 2,408 feet (734 m). Mine Peak at the northwest end of the range has an elevation of 1,850 ft (560 m). Coyote Wash along I-8 along the southeast margin of the range is 100 to 300 feet in elevation. Plaster City lies in the Yuha Desert about 5.5 mi (8.9 km) east of the east end of the range.
The Juncal Formation is a prominent sedimentary geologic unit of Eocene age found in and north of the Santa Ynez Mountain range in southern and central Santa Barbara County and central Ventura County, California. An enormously thick series of sediments deposited over millions of years in environments ranging from nearshore to deep water, it makes up much of the crest of the Santa Ynez range north of Montecito, as well as portions of the San Rafael Mountains in the interior of the county. Its softer shales weather to saddles and swales, supporting a dense growth of brush, and its sandstones form prominent outcrops.
The Jalama Formation is a sedimentary rock formation widespread in southern Santa Barbara County and northern Ventura County, southern California. Of the Late Cretaceous epoch, the unit consists predominantly of clay shale with some beds of sandstone.
Paleontology in Louisiana refers to paleontological research occurring within or conducted by people from the U.S. state of Louisiana. Outcrops of fossil-bearing sediments and sedimentary rocks within Louisiana are quite rare. In part, this is because Louisiana’s semi-humid climate results in the rapid weathering and erosion of any exposures and the growth of thick vegetation that conceal any fossil-bearing strata. In addition, Holocene alluvial sediments left behind by rivers like the Mississippi, Red, and Ouachita, as well as marsh deposits, cover about 55% of Louisiana and deeply bury local fossiliferous strata.
The Alum Bluff Group is a geologic group in the states of Georgia, Florida, and Alabama. It preserves fossils dating back to the Neogene period.
The Mulholland Formation is a Pliocene epoch geologic formation in the Berkeley Hills and San Leandro Hills of the East Bay region of the San Francisco Bay Area, California. It is found within Alameda County and Contra Costa County.
The Orinda Formation is a Miocene epoch geologic formation in the Berkeley Hills of the East Bay region of the San Francisco Bay Area, California.
The Punchbowl Formation is a sedimentary sandstone geologic formation in the northern San Gabriel Mountains, above the Antelope Valley in Los Angeles County, southern California.
The Briones Formation is a Late/Upper Miocene epoch geologic formation of the East Bay region in the San Francisco Bay Area, California.
The Etchegoin Formation is a Pliocene epoch geologic formation in the lower half of the San Joaquin Valley in central California.
The Crowder Formation is a geologic formation in the Central and Western Mojave Desert, in northern Los Angeles County and eastern San Bernardino County, in Southern California.
The Tulare Formation is a Pliocene to Holocene epoch geologic formation in the central and southern San Joaquin Valley of central California.
The San Joaquin Formation is a Pliocene epoch geologic formation in the lower half of the San Joaquin Valley in central California.
The San Benito Gravels is a Quaternary Epoch geologic formation in California.
The Columbus Basin is a foreland basin located off the south eastern coast of Trinidad within the East Venezuela Basin (EVB). Due to the intensive deformation occurring along the Caribbean and South American plates in this region, the basin has a unique structural and stratigraphic relationship. The Columbus Basin has been a prime area for hydrocarbon exploration and production as its structures, sediments and burial history provide ideal conditions for generation and storage of hydrocarbon reserves. The Columbus Basin serves as a depocenter for the Orinoco River delta, where it is infilled with 15 km of fluvio-deltaic sediment. The area has also been extensively deformed by series of north west to southeast normal faults and northeast to southwest trending anticline structures.
The Kootenay Group, originally called the Kootenay Formation, is a geologic unit of latest Jurassic to earliest Cretaceous age in the Western Canada Sedimentary Basin that is present in the southern and central Canadian Rockies and foothills. It includes economically important deposits of high-rank bituminous and semi-anthracite coal, as well as plant fossils and dinosaur trackways.
The geology of California is highly complex, with numerous mountain ranges, substantial faulting and tectonic activity, rich natural resources and a history of both ancient and comparatively recent intense geological activity. The area formed as a series of small island arcs, deep-ocean sediments and mafic oceanic crust accreted to the western edge of North America, producing a series of deep basins and high mountain ranges.
The Bengal Basin is a sedimentary basin. The term Bengal basin is used to describe geological structure of Bengal region's sedimentary basin. It is spread across the Indian states of West Bengal and Bangladesh. The Bengal basin in the eastern part of the Indian subcontinent forms the world's largest fluvio-delta and shallow marine sedimentary basin. This shallow marine sedimentary basin coupled with the Bengal Fan beneath the Bay of Bengal to form the largest sedimentary dispersal system known in the modern world.
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