scholarly journals Climatic Conditions in the Western and Northern Cordillera During the Last Glaciation: Paleoecological Evidence

2007 ◽  
Vol 45 (3) ◽  
pp. 333-339 ◽  
Author(s):  
Rolf W. Mathewes
Keyword(s):  
Plant Communities ◽  
Vegetation Cover ◽  
Ice Sheet ◽  
Climatic Conditions ◽  
Large Mammals ◽  
Slow Cooling ◽  
Thermal Event ◽  
Last Glaciation ◽  
Cordilleran Ice Sheet ◽  
Tentative Correlation

ABSTRACTIn the southern Cordillera, paleoecological evidence suggests that climate was variable, from cooler than present by up to 3°C, to possibly similar to modern during the Olympia non-glacial interval (> 59 TO 25-29 ka). The development of open subalpine parkland vegetation in lowlands after 25 ka reflects slow cooling to glacial conditions. Assumptions about continuously cold and dry glacial conditions are tested and disputed. Between 18-19 ka, pollen, plant macrofossil and beetle evidence suggest relatively warm and moist conditions in the Fraser/Puget Lowlands. A tentative correlation can be inferred with the recently defined "Hanging Lake thermal event" around 18-22 ka in the unglaciated Yukon. Further work should be done to test this inference. Paleobotanical data suggest that increasing moisture, rather than increased cooling, was responsible for the late Vashon ice advance in the southwestern Cordillera. The controversy regarding the nature of the vegetation cover in eastern Beringia, north of the main Cordilleran ice sheet, is not yet settled, although evidence to date favours a complex mosaic of tundra and "steppe-tundra" plant communities supporting a greater diversity of grazing large mammals than exist in the area today.

Advance of alpine glaciers during final retreat of the Cordilleran ice sheet in the Finlay River area, northern British Columbia, Canada

2008 ◽  
Vol 69 (2) ◽  
pp. 188-200 ◽  
Author(s):  
Thomas R. Lakeman ◽  
John J. Clague ◽  
Brian Menounos
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Ice Age ◽  
Last Glaciation ◽  
Alpine Glaciers ◽  
Cordilleran Ice Sheet

Sharp-crested moraines, up to 120 m high and 9 km beyond Little Ice Age glacier limits, record a late Pleistocene advance of alpine glaciers in the Finlay River area in northern British Columbia. The moraines are regional in extent and record climatic deterioration near the end of the last glaciation. Several lateral moraines are crosscut by meltwater channels that record downwasting of trunk valley ice of the northern Cordilleran ice sheet. Other lateral moraines merge with ice-stagnation deposits in trunk valleys. These relationships confirm the interaction of advancing alpine glaciers with the regionally decaying Cordilleran ice sheet and verify a late-glacial age for the moraines. Sediment cores were collected from eight lakes dammed by the moraines. Two tephras occur in basal sediments of five lakes, demonstrating that the moraines are the same age. Plant macrofossils from sediment cores provide a minimum limiting age of 10,550–10,250 cal yr BP (9230±5014C yr BP) for abandonment of the moraines. The advance that left the moraines may date to the Younger Dryas period. The Finlay moraines demonstrate that the timing and style of regional deglaciation was important in determining the magnitude of late-glacial glacier advances.

Retreat pattern of the Cordilleran Ice Sheet in central British Columbia at the end of the last glaciation reconstructed from glacial meltwater landforms

Boreas ◽  
2013 ◽  
pp. n/a-n/a ◽  
Author(s):  
Martin Margold ◽  
Krister N. Jansson ◽  
Johan Kleman ◽  
Arjen P. Stroeven ◽  
John J. Clague
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Glacial Meltwater ◽  
Last Glaciation ◽  
Cordilleran Ice Sheet

STUDYING OF TERSKO-SULAKSKAYA LOWLAND VEGETATION UNDER THE RESULTS OF GROUND-BASED RESEARCH AND AUTOMATED INTERPRETATION

1970 ◽  
pp. 29-32
Author(s):  
M. I. Dzhalalova ◽  
A. B. Biarslanov ◽  
D. B. Asgerova
Keyword(s):  
Plant Communities ◽  
Satellite Imagery ◽  
Vegetation Cover ◽  
Anthropogenic Impacts ◽  
Species Abundance ◽  
Remote Sensing Data ◽  
Indigenous Communities ◽  
The State ◽  
Anthropogenic Factors ◽  
Internet Resource

The state of plant communities in areas located in the Tersko-Sulak lowland was studied by assessing phytocenotic indicators: the structure of vegetation cover, projective cover, species diversity, species abundance and elevated production, as well as automated decoding methods. There are almost no virgin soils and natural phytocenoses here; all of them have been transformed into agrocenoses (irrigated arable lands and hayfields, rice-trees and pastures). The long-term impact on pasture ecosystems of natural and anthropogenic factors leads to significant changes in the indigenous communities of this region. Phytocenoses are formed mainly by dry-steppe types of cereals with the participation of feather grass, forbs and ephemera, a semi-desert haloxerophytic shrub - Taurida wormwood. At the base of the grass stand is common coastal wormwood and Taurida wormwood - species resistant to anthropogenic influences. Anthropogenic impacts have led to a decrease in the number of species of feed-rich grain crops and a decrease in the overall productivity of pastures. Plant communities in all areas are littered with ruderal species. The seasonal dynamics of the land cover of the sites was estimated by the methods of automatic decoding of satellite images of the Landsat8 OLI series satellite for 2015, dated by the periods: spring - May 20, summer - July 23, autumn - October 20. Satellite imagery data obtained by Landsat satellite with a resolution in the multispectral image of 30 m per pixel, and in the panchromatic image - 10 m per pixel, which correspond to the requirements for satellite imagery to assess the dynamics of soil and vegetation cover. Lower resolution data, for example, NDVI MODIS, does not provide a reliable reflection of the state of soil and vegetation cover under arid conditions. In this regard, remote sensing data obtained from the Internet resource https://earthexplorer.usgs.gov/ was used.

Showing the vegetation cover of flood-plains and river valleys on the Vegetation Map of Kazakhstan and middle Asia

1995 ◽  
pp. 58-66
Author(s):  
N. M. Kalibernova
Keyword(s):  
Plant Communities ◽  
Vegetation Cover ◽  
Flood Plain ◽  
Vegetation Map ◽  
Flood Plains ◽  
Additional Information ◽  
Ground Waters ◽  
The Matrix ◽  
River Valleys ◽  
Former Ussr

The fragment of the legend of the map concerning the vegetation of flood- plains and river-valleys in the subzones of northern and southern deserts is presented in the article. The map is compiled in Department of Vegetspon Geography and Cartography of Komarov Botanical Institute by a large team of botanists-geographers of the former USSR. The nature environments determining the development of vegetation of river-valleys in arid climate are conditioned by the intrazonal factors (alluvial and flood processes) at the background of natural zonal factors. Contrasts of environments and corresponding plant communities manifest themselves first of all. Mineralization of ground waters, salinity of soils, including the alluvial ones, are of essential importance. The practice of vegetation mapping of unstable habitats, to which floodplain landscapes belong, has shown that units of phytocoenological classification is of little use for this purpose. The heterogeneity of vegetation, consisting of short-term unstable serial communities generates a need for typification of space combinations of such phytocoenoses. For this purpose it is convenient to use generalized ecological-dinamic series, including plant communities of all levels within the limits of definite segment of valley. These series are the mapping units on the map. The vegetation of the first terrace is also nessecary to include in a single series with flood-plain vegetation because it has supplementary influence of ground waters. The higher divisions of the legend are based on zonal characters: vegetation of valleys in northern, middle and southern deserts. 13 numbers are used to show the vegetation cover of flood-plains and valleys. Additional 7 numbers are used for the out-of-valley meadow vegetation. The content is enriched by using of the letters by the numbers showing the geographic variants of series and ciphers for combination of series and out-of-series communities. The text legend is supplemented by the matrix (table), showing the subordination of subtitles, zonal position and geographic distribution of divisions. The types of series in the matrix are listed with indication of the main dominant species that gives the additional information on the legend divisions. The author's conclusion is that valley vegetation reveals clearly the zonal features, correlating with zonal (desert) vegetation.

NORTHERN CORDILLERAN ICE SHEET DISPLAYS A DIACHRONOUS RESPONSE TO MIS 4 FORCING, YUKON TERRITORY,CANADA

2019 ◽  
Author(s):  
Brent C. Ward ◽  
◽  
Jeffrey D. Bond ◽  
Derek Cronmiller ◽  
Derek Turner ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Cordilleran Ice Sheet
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