Английская Википедия:Delmar Formation

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The Delmar Formation is a geologic formation best exposed in seashore cliffs at Del Mar and Solana Beach in California, overlayed by Torrey Sandstone.Шаблон:Sfn The formation rocks comprise the barrier barШаблон:Sfn for Los Peñasquitos LagoonШаблон:Sfn and have three sub-facies that can be classified as ancient oyster reefs (Ostrea idrianensis), tidal flats and sublittoral channels and pondsШаблон:Sfn The formation is a result of sedimentary infilling of a large Eocene Delmar lagoonШаблон:Sfn and contains fossils from that period. First identified as "Delmar Sand" by Hanna in 1926.Шаблон:Sfn Frederiksen dates the formation as early Lutetian.Шаблон:Sfn

Appearance

Delmar Formation consists of dark green claystone and mudstone, greenish-gray muddy sandstone, interbeds formed by biostromes of shells of molluscs.Шаблон:Sfn

Setting

Frederiksen places the Delmar Formation and overlaying Torrey Sandstone above the Mount Soledad Formation and below Ardath Shale within the early Lutetian in calcareous nannofossils zone CP12.Шаблон:Sfn

The boundary between Delmar Formation and Torrey Sandstone is not clear-cut, the two facies intermix extensively, it is not unusual to find Delmar strata in between Torrey rocks.Шаблон:Sfn

The Delmar formation can be observed, together with Torrey Sandstone, for 20 kilometers along the seashore, from Encinitas to the Torrey Pines State Park, both extend up to 13 kilometers inland, and are expected to go to farther in the subsurface in the southwestern direction.Шаблон:Sfn

Fossils

The formation contains microfossils (pollen, spores, etc.)Шаблон:Sfn and macrofossils (mollusc shells),Шаблон:Sfn with the latter indicating the brackish water conditions.Шаблон:Sfn Plant material can be also found in the form of remains of grass blades and wood fragments.Шаблон:Sfn

See also

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References

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Sources


Шаблон:California-geologic-formation-stub