Evolution of Phenotypic Diversity in Gasterosteus aculeatus Superspecies on the Pacific Coast of North America

1976 ◽  
Vol 25 (3) ◽  
pp. 211 ◽  
Author(s):  
Michael A. Bell
Keyword(s):  
North America ◽  
Gasterosteus Aculeatus ◽  
Pacific Coast ◽  
Phenotypic Diversity ◽  
The Pacific

Summary of Coastal Geologic Evidence for past Great Earthquakes at the Cascadia Subduction Zone

1995 ◽  
Vol 11 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Brian F. Atwater ◽  
Alan R. Nelson ◽  
John J. Clague ◽  
Gary A. Carver ◽  
David K. Yamaguchi ◽  
...  
Keyword(s):  
British Columbia ◽  
North America ◽  
Subduction Zone ◽  
Forest Soils ◽  
Pacific Coast ◽  
Cascadia Subduction Zone ◽  
Level Change ◽  
The Past ◽  
The Pacific ◽  
Juan De Fuca

Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and shaking along the Pacific coast at the Cascadia subduction zone. Sudden lowering of land accounts for many of the buried marsh and forest soils at estuaries between southern British Columbia and northern California. Sand layers on some of these soils imply that tsunamis were triggered by some of the events that lowered the land. Liquefaction features show that inland shaking accompanied sudden coastal subsidence at the Washington-Oregon border about 300 years ago. The combined evidence for subsidence, tsunamis, and shaking shows that earthquakes of magnitude 8 or larger have occurred on the boundary between the overriding North America plate and the downgoing Juan de Fuca and Gorda plates. Intervals between the earthquakes are poorly known because of uncertainties about the number and ages of the earthquakes. Current estimates for individual intervals at specific coastal sites range from a few centuries to about one thousand years.

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].

scholarly journals Framing "Nova Albion": Marking possession in Richard Hakluyt’s The Principal Navigations, Voyages, Traffiques and Discoveries of the English Nation

Sederi ◽  
2014 ◽  
pp. 47-68
Author(s):  
Colm MacCrossan
Keyword(s):  
North America ◽  
Pacific Coast ◽  
The Pacific ◽  
Sir Walter Ralegh ◽  
History Of ◽  
Territorial Claims

This article examines the textual framing of a cluster of items in Richard Hakluyt’s The Principal Navigations, Voyages, Traffiques and Discoveries of the English Nation (1598-1600) relating to the area on the Pacific coast of North America that Francis Drake named “Nova Albion.” Contextualised in relation to the colonial programmes of Sir Humphrey Gilbert and Sir Walter Ralegh, it explores how a variety of editorial techniques combine to encourage a particular understanding of the history of exploration in this region that privileges English territorial claims over those of Spain. What is revealed is a delicate negotiation of the tensions raised by Hakluyt’s use of pre-existing, mainly non-English materials to attempt to legitimise Drake’s actions by aligning them with the Spanish conquistadorial tradition, while at the same time down-playing the extent and significance of previous Spanish activity in that region.

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