USGS Science⌕ Search

SEARCH · USGS Science

Results for “Coasts”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources
USGS1976

Enhydra and Enhydriodon from the Pacific Coast of North America

Two lineages of the "crab-eating" otter Erihydriodon , from the Old World Miocene and Pliocene, are suggested by the fossil record. One appears to lead to the late Pliocene Enhydriodon sivalensis from Villafranchian-equivalent beds in India and can be characterized by the presence of a parastyle on P 4 and by the location of the protocone of this tooth, which is located as far lingually as is the hypocone. In the other lineage no parastyle is developed on P 4 , the anteroposterior length of the carnassial blade is progressively reduced while the transverse width is increased, and the protocone of P 4 remains in its primitive position anterolateral to the hypocone. The second lineage, insofar as it is known, seems to lead toward the living sea otter Enhydra , particularly so because of the evolutionary direction shown by two species of Enhydriodon from the late Miocene and late Pliocene of California.

Pacific Ocean↗
USGS1978

Igneous and metamorphic petrology of the southwestern Dana Mountains, Lassiter Coast, Antarctic Peninsula

The southwestern Dana Mountains of the southern Antarctic Peninsula are underlain by the western part of a composite concentrically zoned Upper Cretaceous batholith consisting largely of granodiorite. The granodiorite (felsic phase) was intrusive into older heterogeneous gabbro-diorite (mafic phase) which makes up the margin of the batholith. Flat-lying pegmatite bodies and abundant inclusions, roof pendants, and septa of metasedimentary rocks and gabbrodiorite suggest that the granodiorite lies near the roof of the batholith. Petrography, chemistry, field relations, and radiometric age dates indicate that the batholith is part of the Andean intrusive suite, a suite of calc-alkaline plutonic rocks that crops out extensively throughout the Antarctic Peninsula and Chilean and Patagonian Andes. Textural features, mineralogy, and chemical data indicate that both phases of the batholith in the southwestern Dana Mountains have been contaminated by assimilation of the Latady Formation, an Upper Jurassic sequence of shale, siltstone, and sandstone that underlies large parts of the southern Antarctic Peninsula. Composition of the granodiorite also has been modified by assimilation of lesser amounts of the gabbro-diorite phase. Such contaminated plutonic rocks occur in several places in the northern Antarctic Peninsula; the batholith in the southwestern Dana Mountains represents the southernmost exposures of contaminated igneous rocks known from the Antarctic Peninsula. Hornblende andesite dikes cut both the mafic and felsic phases of the batholith. Chemical data imply that the dikes represent small amounts of mafic material remobilized by intrusion of the granodiorite. During the austral summers of 1969

Antarctic Peninsula, Dana Mountains, Lassiter Coas↗
USGS1976

Metagraywacke in the Salinian Block, central Coast Ranges, California: And a possible correlative across the San Andreas Fault

The schist of Sierra de Salinas is a monotonously homogeneous biotite quartzofeldspathic schist with minor amounts of quartzite, amphibolite, and marble that forms a northwest-trending outcrop belt that strikes across parts of the Santa Lucia and Gabilan Ranges and is traceable further south in the subsurface to where it is presumably cut off by the San Andreas fault zone. Chemical composition of the schist is similar to that of "average" graywackes. This large and monotonous terrane of metagraywacke is anomalous in the Salinian block, where a great variety of metamorphic rocks is the general rule. The age of the schist is not known, but it has been intruded by granitic rocks of presumably mid-Cretaceous age. Although it contains somewhat greater amounts of admixed quartzite, amphibolite, and marble, the schist of Portal-Bitter Ridge (Pelona Schist?), on the east side of the San Andreas fault and west of Palmdale, is nevertheless modally and chemically similar to the schist (metagraywacke) of Sierra de Salinas, and I suggest that the two terranes are correlative and once were contiguous.

California↗
USGS2026

Science strategy for Cotoni-Coast Dairies, an onshore unit of the California Coastal National Monument

This science strategy describes the scientific mission of the unit, science previously conducted on or near the unit, and the partners who have given considerable effort to produce this science. Further, it identifies priority science needs, outlines the unit’s plan to meet those science needs in coordination with partners, shares scientific protocols for conducting new research, and identifies systems of communication to help ensure science information generated from this research is shared throughout BLM, with partners, and with the public. These components of the science strategy are intended to help achieve the fundamental goals of the effort: to support and expand partnerships while identifying priority science information needs of unit staff and partners and clearly outlining pathways for conducting, communicating, and applying that science.

California↗
USGS1981

The ecology of intertidal oyster reefs of the South Atlantic Coast: A community profile

The functional role of the intertidal oyster reef community in the southeastern Atlantic coastal zone is described. This description is based on a compilation of published data, as well as some unpublished information presented as hypotheses. The profile is organized in a hierarchical manner, such that relevant details of reef oyster biology (autecology) are presented, followed by a description of the reef community level of organization. Then the reef community is described as a subsystem of the coastal marsh-ecosystem (synecoloqy). This information is also synthesized in a series of nested conceptual models of oyster reefs at the regional level, the drainage basin level, and the individual reef level. The final chapter includes a summary overview and a section on management implications and guidelines. Intertidal oyster reefs are relatively persistent features of the salt marsh estuarine ecosystem in the southeastern Atlantic coastal zone. The average areal extent of the oyster reef subsystem in this larger ecosystem is relatively small (about 0.05%). This proportion does not reflect, however, the functional importance of the reef subsystem in stablizing the marsh, providing food for estuarine consumers, mineralizing organic matter, and providing firm substrates in this otherwise soft environment.

FWS/OBS↗