Late quaternary uplift rates of marine terraces on the Pacific coast of North America, southern Oregon to Baja California sur

1992 ◽  
Vol 15-16 ◽  
pp. 121-133 ◽  
Author(s):  
Daniel R. Muhs ◽  
Thomas K. Rockwell ◽  
George L. Kennedy
Keyword(s):  
North America ◽  
Baja California ◽  
Pacific Coast ◽  
Late Quaternary ◽  
Baja California Sur ◽  
Marine Terraces ◽  
The Pacific ◽  
Uplift Rates

Uranium-Series Ages of Marine Terrace Corals from the Pacific Coast of North America and Implications for Last-Interglacial Sea Level History

1994 ◽  
Vol 42 (1) ◽  
pp. 72-87 ◽  
Author(s):  
Daniel R. Muhs ◽  
George L. Kennedy ◽  
Thomas K. Rockwell
Keyword(s):  
North America ◽  
Sea Level ◽  
Baja California ◽  
Pacific Coast ◽  
Baja California Sur ◽  
Marine Terrace ◽  
San Nicolas Island ◽  
Uranium Series ◽  
Marine Terraces ◽  
The Pacific

AbstractFew of the marine terraces along the Pacific coast of North America have been dated using uranium-series techniques. Ten terrace sequences from southern Oregon to southern Baja California Sur have yielded fossil corals in quantities suitable for U-series dating by alpha spectrometry. U-series-dated terraces representing the ∼80,000 yr sea-level high stand are identified in five areas (Bandon, Oregon; Point Arena, San Nicolas Island, and Point Loma, California; and Punta Banda, Baja California); terraces representing the ∼125,000 yr sea-level high stand are identified in eight areas (Cayucos, San Luis Obispo Bay, San Nicolas Island, San Clemente Island, and Point Loma, California; Punta Bands and Isla Guadalupe, Baja California; and Cabo Pulmo, Baja California Sur). On San Nicolas Island, Point Loma, and Punta Bands, both the ∼80,000 and the ∼125,000 yr terraces are dated. Terraces that may represent the ∼105,000 sea-level high stand are rarely preserved and none has yielded corals for U-series dating. Similarity of coral ages from midlatitude, erosional marine terraces with coral ages from emergent, constructional reefs on tropical coastlines suggests a common forcing mechanism, namely glacioeustatically controlled fluctuations in sea level superimposed on steady tectonic uplift. The low marine terrace dated at ∼125,000 yr on Isla Guadalupe, Baja California, presumed to be tectonically stable, supports evidence from other localities for a +6-m sea level at that time. Data from the Pacific Coast and a compilation of data from other coasts indicate that sea levels at ∼80,000 and ∼105,000 yr may have been closer to present sea level (within a few meters) than previous studies have suggested.

scholarly journals MIS 5e sea-level history along the Pacific Coast of North America

2021 ◽  
Author(s):  
Daniel R. Muhs
Keyword(s):  
North America ◽  
Sea Level ◽  
Baja California ◽  
Pacific Coast ◽  
Level Indicator ◽  
Sequence Of Events ◽  
Marine Terraces ◽  
The Pacific ◽  
Mis 5E ◽  
Good Agreement

Abstract. The primary last interglacial, marine isotope substage (MIS) 5e records on the Pacific Coast of North America, from Washington (USA) to Baja California Sur (Mexico), are found in the deposits of erosional marine terraces. Warmer coasts along the southern Golfo de California host both erosional marine terraces and constructional coral reef terraces. Because the northern part of the region is tectonically active, MIS 5e terrace elevations vary considerably, from a few meters above sea level to as much as 70 m above sea level. The primary paleo-sea level indicator is the shoreline angle, the junction of the wave-cut platform with the former sea cliff, which forms very close to mean sea level. Most areas on the Pacific Coast of North America have experienced uplift since MIS 5e time, but the rate of uplift varies substantially as a function of tectonic setting. Chronology in most places is based on uranium-series ages of the solitary coral Balanophyllia elegans (erosional terraces) or the colonial corals Porites and Pocillopora (constructional reefs). In areas lacking corals, correlation to MIS 5e can sometimes be accomplished using amino acid ratios of fossil mollusks, compared to similar ratios in mollusks that also host dated corals. U-series analyses of corals that have experienced largely closed-system histories range from ~124 to ~118 ka, in good agreement with ages from MIS 5e reef terraces elsewhere in the world. There is no geomorphic, stratigraphic, or geochronology evidence for more than one high-sea stand during MIS 5e on the Pacific Coast of North America. However, in areas of low uplift rate, the outer parts of MIS 5e terraces apparently were re-occupied by the high-sea stand at ~100 ka (MIS 5c), evident from mixes of coral ages and mixes of molluscan faunas with differing thermal aspects. This sequence of events took place because glacial isostatic adjustment processes acting on North America resulted in regional high-sea stands at ~100 ka and ~80 ka that were higher than is the case in far-field regions, distant from large continental ice sheets. During MIS 5e time, sea surface temperatures (SST) off the Pacific Coast of North America were higher than is the case at present, evident from extralimital southern species of mollusks found in dated deposits. Apparently no wholesale shifts in faunal provinces took place, but in MIS 5e time, some species of bivalves and gastropods lived hundreds of kilometers north of their present northern limits, in good agreement with SST estimates derived from foraminiferal records and alkenone-based reconstructions in deep-sea cores. Because many areas of the Pacific Coast of North America have been active tectonically for much or all of the Quaternary, many earlier interglacial periods are recorded as uplifted, higher elevation terraces. In addition, from southern Oregon to northern Baja California, there are U-series-dated corals from marine terraces that formed ~80 ka, during MIS 5a. In contrast to MIS 5e, these terrace deposits host molluscan faunas that contain extralimital northern species, indicating cooler SST at the end of MIS 5. Here I present a standardized database of MIS 5e sea-level indicators along the Pacific Coast of North America and the corresponding dated samples. The database is available in Muhs (2021)  [https://doi.org/10.5281/zenodo.5557355].

A new genus of cassiduloid echinoid from the lower Eocene of the Pacific coast of western North America and a new report of Cassidulus ellipticus Kew, 1920, from the lower Eocene of Baja California Sur, Mexico

1995 ◽  
Vol 69 (3) ◽  
pp. 509-515 ◽  
Author(s):  
Richard L. Squires ◽  
Robert A. Demetrion
Keyword(s):  
North America ◽  
New Genus ◽  
Baja California ◽  
Pacific Coast ◽  
Middle Part ◽  
Baja California Sur ◽  
Western North America ◽  
Lower Eocene ◽  
Shallow Marine ◽  
The Pacific

The cassiduloid echinoid Calilampas californiensis n. gen. and sp. is described from middle lower Eocene (“Capay Stage”) shallow-marine sandstones in both the middle part of the Bateque Formation, Baja California Sur, Mexico, and the lower part of the Llajas Formation, southern California. The new genus is tentatively placed in family Pliolampadidae. The cassiduloid Cassidulus ellipticus Kew, 1920, previously known only from the “Capay Stage” in California, is also present in “Capay Stage” shallow-marine sandstones of the Bateque Formation.

Middle Eocene terebratulide brachiopods from the Bateque Formation, Baja California Sur, Mexico

1995 ◽  
Vol 69 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Michael R. Sandy ◽  
Richard L. Squires ◽  
Robert Demetrion
Keyword(s):  
North America ◽  
Baja California ◽  
Pacific Coast ◽  
Middle Eocene ◽  
Central American ◽  
Baja California Sur ◽  
Invertebrate Fauna ◽  
The West ◽  
The Pacific ◽  
Central American Seaway

Two species of terebratulide brachiopods are described from the upper part of the Bateque Formation (middle Eocene) on the Pacific coast of Baja California Sur, Mexico, Terebratulina cf. Terebratulina louisianae Stenzel, 1940, and Terebratalia batequia n. sp. Terebratalia batequia n. sp. is the earliest confirmed record of the genus Terebratalia Beecher, 1893, which has been an important component of Pacific brachiopod faunas through to the present day. The occurrence of Terebratulina cf. Terebratulina louisianae Stenzel is one of the earliest records of the genus from the west coast of North America. These brachiopods, like other elements of the Bateque invertebrate fauna, may record Eocene migration from the Atlantic to Pacific Ocean via the Central American seaway.

scholarly journals The artisanal elasmobranch fishery of the Pacific coast of Baja California Sur, Mexico, management implications

2013 ◽  
Vol 77 (3) ◽  
pp. 473-487 ◽  
Author(s):  
Felipe Galvan-Magaña ◽  
Sergio R. Ramirez-Amaro ◽  
Daniel Cartamil ◽  
Gerardo Gonzalez-Barba ◽  
Jeffrey B. Graham ◽  
...  
Keyword(s):  
Baja California ◽  
Pacific Coast ◽  
Baja California Sur ◽  
Management Implications ◽  
The Pacific

scholarly journals SMALL-SCALE SHRIMP FISHING IN SEARCH OF SUSTAINABILITY IN THE MAGDALENA-ALMEJAS LAGOON SYSTEM, BAJA CALIFORNIA SUR, MÉXICO: A REVIEW

2016 ◽  
Vol 31 (1) ◽  
pp. 45
Author(s):  
Ludwig Naegel ◽  
Mauricio Muñoz-Ochoa ◽  
Lorena Maria Durán-Riverol
Keyword(s):  
Baja California ◽  
Pacific Coast ◽  
Marine Conservation ◽  
Small Scale ◽  
Baja California Sur ◽  
Lagoon System ◽  
The Pacific ◽  
El Sistema ◽  
Large Water ◽  
Bahia Magdalena

The coastal lagoon system Bahía Magdalena / Almejas (BM/A) at the Pacific coast of Baja California Sur, México, is a large water body extremely important for ecological, economic and social reasons. Because of its natural environment BM/A was declared as one of the areas deserving marine conservation priority. The exact number of fishermen and their families living around the Bay is not known, and neither is the currently registered small boats in service, nor the fishing efforts, expenses and yields. Recently, several civil organizations started working in the BM/A with the mission to solve some of the identified environmental and social problems. However, because of the lack of reliable data, wide spread corruption, and undirected and uncoordinated research make it very difficult to suggest ways to improve the livelihood of the small-scale shrimp fishermen without endangering the environment. Some promising options are small-scale aquaculture projects, mainly for off-shore mollusks production, and to offer eco-tourist activities as well as eco-friendly sport fishing. Both bring local employment opportunities while maintaining a quality environment. En busca de sustentabilidad de la pesquería de camarón a baja escala en el sistema lagunar Magdalena-Almejas Baja California Sur, México: una revisión El sistema lagunar Bahía Magdalena / Almejas (BM/A) ubicado en la costa oeste de Baja California Sur, México, es un cuerpo de agua de extrema importancia bajo las perspectivas ecológica, económica y social. Dado su ambiente natural, BM/A es considerada un área prioritaria en términos de conservación marina. Se desconoce cuántas familias de pescadores viven entorno a la bahía, así como el número registrado de embarcaciones pequeñas en activo, el esfuerzo pesquero, sus gastos, o su rendimiento. Recientemente, varias organizaciones civiles comenzaron labores en BM/A bajo la consigna de resolver algunos de los problemas ambientales y sociales identificados. Sin embargo, debido a la falta de datos confiables y a la corrupción, aunados a investigación mal dirigida y sin coordinación, dificultan la posibilidad de sugerir maneras de mejorar la sustentabilidad de la pesca menor de camarón sin poner en riesgo el ambiente. Algunas alternativas prometedoras son los proyectos acuaculturales a pequeña escala, principalmente para producción de moluscos lejos de la costa, así como las actividades ecoturísticas y la pesca deportiva ecológicamente amigable, dado que ambas abren oportunidades de empleo locales conservando la calidad del ambiente.

New Paleogene Fimbria (Mollusca: Bivalvia) from the Pacific Coast of southwestern North America

1990 ◽  
Vol 64 (4) ◽  
pp. 552-556 ◽  
Author(s):  
Richard L. Squires
Keyword(s):  
New Species ◽  
North America ◽  
Late Cretaceous ◽  
Southern California ◽  
Pacific Coast ◽  
Late Eocene ◽  
Marine Bivalve ◽  
Baja California Sur ◽  
Lower Eocene ◽  
The Pacific

The marine bivalve Fimbria susanensis n. sp. is reported from the uppermost Paleocene part of the “Meganos Stage” in the upper Santa Susana Formaton, Simi Hills, southern California.Fimbria pacifica n. sp. is reported from the middle lower Eocene “Capay Stage” strata of the Pacific coast of southwestern North America. The new species is present in the lower Bateque Formation, Baja California Sur, Mexico, and in the lower Juncal Formation, Whitaker Peak area and Santa Ynez Mountains, southern California.Fimbria susanensis n. sp. and F. pacifica n. sp. are the only fimbriids known from the Pacific coast of North America. Previously reported Pacific coast species, which gave a range of Late Cretaceous to late Eocene for this genus in this particular area, do not belong to Fimbria.

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