SUMMARY / RELATED TOPICS

Von Schrenck's bittern

Von Schrenck's bittern known as Schrenck's bittern, is a small bittern. It breeds in China and Siberia from March to July, Japan from May to August, it winters in Indonesia, Singapore, passing through the rest of South-east Asia. It is an exceptionally rare vagrant as far west as Europe, with a single sighting in Italy in 1912, it is named after the 19th-century Russian naturalist. This is a small species at 33 to 38 cm in length, with a short neck, longish yellow bill and yellow legs; the male is uniformly chestnut above, buff below and on the wing coverts. The female and juvenile are chestnut all over with white speckles above, white streaks below; when in flight, it shows black flight feathers and tail. Their breeding habitat is reed beds, they can be difficult to see, given their skulking lifestyle and reed bed habitat, but tend to emerge at dusk, when they can be seen creeping cat-like in search of preys. Widespread throughout its large range, Von Schrenck's bittern is evaluated as Least Concern on the IUCN Red List of Threatened Species.

BirdLife Species Factsheet

Vaqueros Formation

The Vaqueros Formation is a sedimentary geologic unit of Upper Oligocene and Lower Miocene age, widespread on the California coast and coastal ranges in the southern half of the state. It is predominantly a medium-grained sandstone unit, deposited in a shallow marine environment; because of its high porosity and nearness to petroleum source rocks, in many places it is an oil-bearing unit, wherever it has been configured into structural or stratigraphic traps by folding and faulting. Being resistant to erosion, it forms dramatic outcrops in the coastal mountains, its color ranges from grayish-green to light gray when freshly broken, it weathers to a light brown or buff color. The type locality of the Vaqueros is from Vaqueros Canyon in the Santa Lucia Mountains, about eight miles southwest of Greenfield; the formation was first described by Homer Hamlin in 1904, as part of a report on the water resources of the Salinas Valley. The sandstone unit consists of well-sorted grains, averaging medium-size quartz and feldspar with some black flecks, in form it ranges from cross-bedded to massive and thick-bedded.

It contains pebbles near its base where it sits on the red non-marine Sespe Formation. Some fossils – including mollusks and barnacles – can be found in the Vaqueros near the base of the unit where the depositional environment was nearest shore; the unit was deposited by runoff from highlands to the east into a shallow, warm marine environment, as the ocean transgressed on the subsiding floodplain containing the Sespe in the late Oligocene age, between 26 and 28 Ma to 24 to 25 Ma. As the land continued to subside, the ocean depth increased with a corresponding drop in grain size in higher strata; the topmost part of the Vaqueros contains interbedded mudstones and fine-grained sandstones, representing this shift. The unit above the Vaqueros, the Rincon Formation, consists of deepwater shales; the Vaqueros weathers to a clayey soil which supports chaparral, on the southern slopes of the Santa Ynez Mountains in southern Santa Barbara County, its contact with the Rincon Formation is visible for it correlates to the line where the grassland or coastal sage scrub, nearer the coast, abruptly changes to dense chaparral on the mountainside.

Fossils found in the Vaqueros are near-shore marine organisms, such as mollusks and oysters While the molluscan stage is hard to date and ranges from the Miocene epoch, strata from Simi Valley have sampled in the upper Oligocene period. In some places, the Vaqueros has been deformed into anticlinal structures, or pinched out into structural traps, allowing petroleum to become trapped in economically recoverable quantities; some locations where this has occurred include the Ellwood and Mesa Oil Fields in Santa Barbara County, the Kettleman North Dome and Coalinga Oil Fields in the Central Valley. When grouped with the underlying Sespe Formation, because of its high porosity and the presence of an impermeable cap in the overlying Rincon Formation, it is the second-most important producing horizon in Southern California. C. Michael Hogan, Leda Patmore, David Crimp et al. San Lorenzo Basin Groundwater Recharge and Water Quality Study, Earth Metrics Incorporated, Association of Monterey Bay Area Governments, July 7, 1978 United States Geological Survey.

1921. Bulletin, Volume 721, US Government Printing Office, Washington DC