The continental margin of the eastern United States

1968 ◽  
Vol 5 (4) ◽  
pp. 993-1010 ◽  
Author(s):  
Charles L. Drake ◽  
John I. Ewing ◽  
Henry Stockard
Keyword(s):  
United States ◽  
New England ◽  
Continental Margin ◽  
Magnetic Measurements ◽  
Large Body ◽  
Ocean Basin ◽  
Eastern United States ◽  
Geological Data ◽  
The Bahamas ◽  
Reflection And Refraction

Geophysical and geological data of many types are now available from the continental margin of the eastern United States. These include seismic reflection and refraction data, gravity and magnetic measurements, cores of sediments and dredge hauls of rocks, underwater photographs, echo sounding data, and a large body of surface and subsurface geological data from the adjacent land.Major differences in the sedimentary pattern and sedimentary types occur from north to south and reflect not only source differences but also differences in means of transport and deposition. The data indicate a continuity of structure from Newfoundland to the Bahamas, interrupted only by the Kelvin-New England seamount group and associated structures ashore. They suggest that the ocean basin west of Bermuda is at least as old as Paleozoic.

Vegetation East of the Rocky Mountains 18,000 Years Ago

1981 ◽  
Vol 15 (2) ◽  
pp. 113-125 ◽  
Author(s):  
H.E. Wright
Keyword(s):  
United States ◽  
Boreal Forest ◽  
New England ◽  
Jack Pine ◽  
Atlantic Coastal Plain ◽  
Reference Level ◽  
Eastern United States ◽  
Southern Limit ◽  
Southern Georgia ◽  
Narrow Belt

AbstractThe various lobes and segments of the southern periphery of the Laurentide ice sheet reached their maximum extension at different times between 21,000 and 14,000 yr ago, but the CLIMAP date of 18,000 yr ago is taken as a reference level to review the distribution of major vegetational formations in central and eastern United States. Tundra was apparently confined to a narrow belt peripheral to the ice margin only in the Minnesota area and from northern Pennsylvania to New England, with extensions down the crest of the Appalachian Highlands at least as far as Maryland. Some areas south of the Great Lakes may later have been marked by treeless vegetation briefly as the ice retreated. The boreal forest to the south in the central United States was dominated by spruce; the jack pine that had prevailed during previous times was apparently eliminated by the time the ice reached its maximum. In the Appalachian Highlands and the Atlantic Coastal Plain, however, jack pine occurred along with spruce, which decreased in importance southward. The southern limit of the boreal forest in the Southeast was perhaps somewhere in southern Georgia and Alabama. Oak and other temperate deciduous trees were minor components of the boreal coniferous forests especially in the southern Appalacchians, but there is no evidence yet in the southeastern states for a relic mixed mesophytic forest 18,000 yr ago similar to the rich modern deciduous forests of the region, except possibly in the Lower Mississippi Valley. The climate in much of the Southeast was apparently dry as well as cool at that time; in Florida oak/pine scrub and prairie-like openings prevailed, and all but the deepest lakes dried up.

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