scholarly journals Distribution of Surging Glaciers in Western North America

1969 ◽  
Vol 8 (53) ◽  
pp. 229-240 ◽  
Author(s):  
Austin Post
Keyword(s):  
North America ◽  
Sierra Nevada ◽  
Cascade Range ◽  
Western North America ◽  
Geothermal Heat ◽  
Alaska Range ◽  
Coast Mountains ◽  
Glacier Bay ◽  
Olympic Mountains ◽  
Restricted Distribution

In western North America 204 surging glaciers have been identified by aerial photographic observations. These glaciers exhibit either intense crevassing and rapid ice displacements during surges or distinctive surface features which have resulted from past surges. Distribution of these unusual glaciers is not random throughout the glacierized areas, as they occur only in the Alaska Range, eastern Wrangell Mountains, eastern Chugach Mountains, Icefield Ranges, and the St Elias Mountains near Yakutat and Glacier Bay. No surging glaciers have been identified in the Brooks Range, Kenai Mountains, west and central Chugach Mountains, west and central Wrangell Mountains, Coast Mountains, Rocky Mountains, Cascade Range, Olympic Mountains, or Sierra Nevada. No definite reason for this restricted distribution is apparent. Surging glaciers are found in maritime to continental and temperate to subpolar environments. Practically all physical forms of glaciers are represented. The restricted distribution does not relate to topography, bedrock type, altitude, orientation, or size of glacier. Some surging glaciers are associated with fault-related valleys, but neither recent faulting nor earthquakes have initiated surge activity. Possible causes for the limited distribution of surges are unusual bedrock roughness or permeability in certain areas, anomalously high ground-water temperatures, and/or abnormal geothermal heat flow.

scholarly journals Distribution of Surging Glaciers in Western North America

1969 ◽  
Vol 8 (53) ◽  
pp. 229-240 ◽  
Author(s):  
Austin Post
Keyword(s):  
North America ◽  
Sierra Nevada ◽  
Cascade Range ◽  
Western North America ◽  
Geothermal Heat ◽  
Alaska Range ◽  
Coast Mountains ◽  
Glacier Bay ◽  
Olympic Mountains ◽  
Restricted Distribution

In western North America 204 surging glaciers have been identified by aerial photographic observations. These glaciers exhibit either intense crevassing and rapid ice displacements during surges or distinctive surface features which have resulted from past surges. Distribution of these unusual glaciers is not random throughout the glacierized areas, as they occur only in the Alaska Range, eastern Wrangell Mountains, eastern Chugach Mountains, Icefield Ranges, and the St Elias Mountains near Yakutat and Glacier Bay. No surging glaciers have been identified in the Brooks Range, Kenai Mountains, west and central Chugach Mountains, west and central Wrangell Mountains, Coast Mountains, Rocky Mountains, Cascade Range, Olympic Mountains, or Sierra Nevada. No definite reason for this restricted distribution is apparent. Surging glaciers are found in maritime to continental and temperate to subpolar environments. Practically all physical forms of glaciers are represented. The restricted distribution does not relate to topography, bedrock type, altitude, orientation, or size of glacier. Some surging glaciers are associated with fault-related valleys, but neither recent faulting nor earthquakes have initiated surge activity. Possible causes for the limited distribution of surges are unusual bedrock roughness or permeability in certain areas, anomalously high ground-water temperatures, and/or abnormal geothermal heat flow.

Mountain Climates of North America

2000 ◽  
Author(s):  
C. David Whiteman
Keyword(s):  
United States ◽  
North America ◽  
Sierra Nevada ◽  
Rocky Mountains ◽  
Climatic Conditions ◽  
Cascade Range ◽  
Coast Range ◽  
Alaska Range ◽  
Mountain Ranges ◽  
The Pacific

The basic climatic characteristics of the major mountain ranges in the United States—the Appalachians, the Coast Range, the Alaska Range, the Cascade Range, the Sierra Nevada, and the Rocky Mountains—can be described in terms of the four factors discussed in chapter 1. The mountains of North America extend latitudinally all the way from the Arctic Circle (66.5°N) to the tropic of Cancer (23.5°N) (figure 2.1). There are significant differences in day length and angle of solar radiation over this latitude belt that result in large seasonal and diurnal differences in the weather from north to south. Elevations in the contiguous United States extend from below sea level at Death Valley to over 14,000 ft (4270 m) in the Cascade Range, the Sierra Nevada, and the Rocky Mountains. Several prominent peaks along the Coast Range in Alaska and Canada (e.g., Mount St. Elias and Mount Logan) reach elevations above 18,000 ft (5486 m). Denali (20,320 ft or 6194 m) in the Alaska Range is the highest peak in North America. The highest peak in the Canadian Rockies is Mt. Robson, with an elevation of 12,972 ft (3954 m). The climates of the Coast Range, the Cascade Range, and the Sierra Nevada, all near the Pacific Ocean, are primarily maritime. The Appalachian Mountains of the eastern United States are subject to a maritime influence from the Atlantic Ocean and the Gulf of Mexico, but they are also affected by the prevailing westerly winds that bring continental climatic conditions. Only the climate of the Rocky Mountains, far from both the Pacific and Atlantic Oceans, is primarily continental. Each of the mountain ranges is influenced by regional circulations. For example, the Appalachians are exposed to the warm, moist winds brought northward by the Bermuda-Azores High and to the influence of the Gulf Stream. Similarly, the Coast Range feels the impact of the Pacific High, the Aleutian low, and the Japanese Current. A mountain range, depending on its size, shape, orientation, and location relative to air mass source regions, can itself affect the regional climate by acting as a barrier to regional flows.

Penutian Languages

2018 ◽  
Author(s):  
Anthony P. Grant
Keyword(s):  
North America ◽  
Sierra Nevada ◽  
Current Knowledge ◽  
Language Family ◽  
Western North America

The Penutian language family, Penutian phylum, or better still, Penutian hypothesis is one of the largest genealogical linguistic groupings to have been proposed for western North America. It involves 16 families or isolates. Only a few of these families are demonstrably relatable to one another according to current knowledge and diachronic techniques. Sometimes Penutian is split by observers into groups of languages assumed to be interrelated, and this is done without assumptions that the groups themselves are interrelated. This article focuses on the Canadian and US languages in “Sapir’s Penutian,” the most commonly accepted version; the most southerly family within Penutian is thus held as Yokutsan of California’s Sierra Nevada. It discusses the subclassification of the so-called Penutian languages into families and smaller units; aspects of their phonology, morphosyntax, and contact histories; and issues in their revitalization and the potential reconstruction of Proto-Penutian.

Middle Miocene through Pliocene North American Vegetational History: 16.3-1.6 Ma

1999 ◽  
Author(s):  
Alan Graham
Keyword(s):  
North America ◽  
Sierra Nevada ◽  
North American ◽  
Middle Miocene ◽  
Middle Eocene ◽  
Alaska Range ◽  
Seasonally Dry ◽  
Middle Latitudes ◽  
The North ◽  
Dry Climates

During the Middle Miocene through the Pliocene the Appalachian Mountains underwent continued erosion and approached modern elevations. The Rocky Mountains had undergone uplift to half or more of their present elevation during the Late Cretaceous to Middle Eocene Laramide Revolution; after a lull during the Middle Eocene through the Early Miocene, there was increased tectonic activity beginning ~12 Ma and especially between 7 and 4 Ma. Locally some highlands may have approached or attained modern elevations. The increasingly high mountains and plateaus of Asia and North America deflected the major air streams southward, bringing colder polar air into the middle latitudes of North America. An extensive Antarctic ice sheet further cooled ocean waters and contributed to the spread of seasonally dry climates. The elimination of most of the Asian exotics from the North American flora dates to the Late Miocene-Pliocene as a result of a decline in summer rainfall. The Sierra Nevada attained about two-thirds of their present elevation within the past 10 Ma. They were appreciably elevated at ~5 Ma, stood at ~2100 m at 3 Ma, and have risen ~950 m since 3 Ma (Huber, 1981). The California Coast Ranges and Cascade Mountains attained significant heights by 3 Ma, and there was a rapid rise of the Alaska Range at ~6 Ma. Temperatures increased between ~18 and 16 Ma. In the absence of major plate reorganization and intense volcanic activity and with increased erosion from continued replacement of the dense evergreen forest by deciduous forest and shrubland (increasing albedo), atmospheric CO2 concentration decreased and a sharp lowering of temperature occurred in the Middle Miocene between 15 and 10 Ma. Eolian dust deposits increased in the Late Cenozoic, suggesting greater aridity (Rea et al., 1985). This is supported by kaolinite records from North Atlantic deep sea sediments (Chamley, 1979). At ~4.8~4.9 Ma global cooling and a marine regression of ~40~50 m combined to isolate the Mediterranean Basin from the ocean and to concentrate large volumes of salt as water evaporated. The biota was destroyed, giving rise to the term Messinian salinity crisis.

Denali-Yukon, Domain 9

2007 ◽  
Author(s):  
Earl B. Alexander ◽  
Roger G. Coleman ◽  
Todd Keeler-Wolfe ◽  
Susan P. Harrison
Keyword(s):  
British Columbia ◽  
North America ◽  
Yukon Territory ◽  
Ultramafic Rocks ◽  
Mean Annual Precipitation ◽  
Alaska Range ◽  
Coast Mountains ◽  
Denali Fault ◽  
Ice Caps ◽  
Mountain Glaciers

The Denali-Yukon domain occupies a broad arc that, in general, follows the path of the Denali Fault along the Alaska Range and southwestward into the Yukon Territory. An ophiolite in the northwestern corner of British Columbia that is northeast of the projected Denali fault is included in this locality. A projection of the Denali fault system southwestward from the Alaska Range passes through the southwestern part of the Ahklun Mountains physiographic province, as the province was defined by Wahrhaftig (1965), to Kuskokwim Bay between the mouth of the Kuskowim River and Cape Newenham. Three mafic–ultramafic complexes on the southwestern edge of the Ahklun Mountains province are included in this domain. Glaciers covered this entire domain during the Pleistocene, and mountain glaciers and ice caps are still present at the higher elevations. Permafrost is currently discontinuous. The highest mountain in North America (Mt. McKinley, 6194 m) is in the Alaska Range, but the ultramafic rocks are all at much lower elevations. The climate is very cold throughout the domain, with severe winters and short summers. The mean annual precipitation ranges from 45 to150 cm in the Ahklun Mountains, from 30 to 60 cm in the Alaska Range, and from 30 to 75 cm, or more, in the Atlin area of northwestern British Columbia, which is in the rain shadow of the Coast Mountains. The greatest precipitation is during summers, from June or July to September or October. The frostfree period is on the order of 60–90 days, or shorter, but it may be longer in some of the Atlin area of British Columbia. Localities 9-1 through 9-3 are from Cape Newenham northeastward in the Ahklun Mountains. The ultramafic rocks in the Cape Newenham area were accreted to North America by north directed thrust faults during the Late Triassic and Middle Jurassic time. Localities 9-4 through 9-7 are in the Alaska Range. Locality 9-8 is along a projection of the Denali fault to the eastern edge of the Coast Ranges in British Columbia.

Millennial-scale variations in western Sierra Nevada precipitation during the last glacial cycle MIS 4/3 transition

2014 ◽  
Vol 82 (1) ◽  
pp. 236-248 ◽  
Author(s):  
Jessica L. Oster ◽  
Isabel P. Montañez ◽  
Regina Mertz-Kraus ◽  
Warren D. Sharp ◽  
Greg M. Stock ◽  
...  
Keyword(s):  
North America ◽  
Sierra Nevada ◽  
Western Slope ◽  
Western North America ◽  
Glacial Cycle ◽  
Climatic Response ◽  
Last Glacial ◽  
Mis 3 ◽  
Heinrich Event ◽  
The Last Glacial

AbstractDansgaard–Oeschger (D–O) cycles had far-reaching effects on Northern Hemisphere and tropical climate systems during the last glacial period, yet the climatic response to D–O cycles in western North America is controversial, especially prior to 55 ka. We document changes in precipitation along the western slope of the central Sierra Nevada during early Marine Oxygen Isotope Stages (MIS) 3 and 4 (55–67 ka) from a U-series dated speleothem record from McLean's Cave. The timing of our multi-proxy geochemical dataset is coeval with D–O interstadials (15–18) and stadials, including Heinrich Event 6. The McLean's Cave stalagmite indicates warmer and drier conditions during Greenland interstadials (GISs 15–18), signified by elevated δ18O, δ13C, reflectance, and trace element concentrations, and less radiogenic 87Sr/86Sr. Our record extends evidence of a strong linkage between high-latitude warming and reduced precipitation in western North America to early MIS 3 and MIS 4. This record shows that the linkage persists in diverse global climate states, and documents the nature of the climatic response in central California to Heinrich Event 6.

Chronostratigraphy of glaciations and permafrost episodes in the Cordillera of western North America

1994 ◽  
Vol 18 (3) ◽  
pp. 366-395 ◽  
Author(s):  
Stuart A. Harris
Keyword(s):  
North America ◽  
Climatic Change ◽  
Sierra Nevada ◽  
Late Miocene ◽  
Complete Sequence ◽  
Lava Flows ◽  
Radiometric Dating ◽  
Western North America ◽  
Quaternary Period ◽  
Cold Events

Glaciations in the Cordillera of western North America began during the Late Miocene in the St Elias Range and coastal ranges near Anchorage, Alaska. Radiometric dating of the tephra and lava flows intercalated in the succession of older tills, loesses and outwash deposits permits the reconstruction of the probable early glacial sequence along the Cordillera. No one site shows the complete sequence, but the available data suggest synchroneity of the major glacial events throughout the region. The first evidence for cold conditions at low elevations at midlatitudes is from 3.5 Ma BP. By 2.8 Ma, alpine glaciations may have occurred in the Sierra Nevada and ice wedges had formed in bedrock near Fairbanks, Alaska. Three more major glaciations complete with contemporary periglacial and permafrost landforms had occurred by 1.65 Ma, while at least six more major cold events can be recognized during the Quaternary period. Once again, expansion of permafrost conditions occurred during each event and forms an integral part of the evidence for climatic change.

Genetics of Cronartium ribicola. IV. Population structure in western North America

1998 ◽  
Vol 76 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Bohun B Kinloch, Jr. ◽  
Robert D Westfall ◽  
Eleanor E White ◽  
Matthew A Gitzendanner ◽  
Gayle E Dupper ◽  
...  
Keyword(s):  
North America ◽  
Sierra Nevada ◽  
Genetic Drift ◽  
Tandem Repeats ◽  
Polymorphic Locus ◽  
Random Amplified Polymorphic Dna ◽  
Rflp Markers ◽  
Cronartium Ribicola ◽  
Western North America ◽  
Multiple Alleles

Population genetic parameters were estimated for six populations of Cronartium ribicola in western North America from British Columbia to the southern Sierra Nevada, and two outgroups from eastern North America, using isozyme, random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) markers on cultured haploid clones. Diversity was low, with only 8% polymorphism in the 212 markers identified. Each polymorphic locus had only two alleles, except for an RFLP marker in the ribosomal DNA complex with multiple alleles, that resulted from variable numbers of tandem repeats. Expected heterozygosity within populations, estimated from diploid teliospores, was only 0.025. The three types of markers were highly consistent with each other for these parameters. Yet, populations were highly differentiated; the proportion of the total variation attributable to differences among populations was 0.205. Multivariate statistical analysis as well as different clustering algorithms based on contrasting evolutionary assumptions (drift, mutation) all showed similar relationships and differences among populations. Genetic distances were not associated with geographic distances; western populations within a few kilometres of each other were often more distant from each other genetically than they were from eastern populations across the continent. The lack of pattern over the landscape of this metapopulation is consistent with aspects of the life cycle and epidemiological behavior of the pathogen, in which genetic drift appears to play a major role.Key words: white pine blister rust, isozymes, RAPDs, RFLPs, multivariate analysis, genetic drift.

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