History of Forest Service Research in the Central and Southern Rocky Mountain Regions, 1908–1975. By Raymond Price and Frontiers of Forestry Research-Priest River Experimental Forest, 1911–1976. By Charles A. Wellner

1977 ◽  
Vol 21 (3) ◽  
pp. 168-169
Author(s):  
V. L. Harper
Keyword(s):  
Rocky Mountain ◽  
Forest Service ◽  
Service Research ◽  
Mountain Regions ◽  
Forestry Research ◽  
History Of ◽  
Southern Rocky Mountain

The St. Eugene Formation and the Development of the Southern Rocky Mountain Trench

1974 ◽  
Vol 11 (7) ◽  
pp. 916-938 ◽  
Author(s):  
John J. Clague
Keyword(s):  
Rocky Mountain ◽  
Flood Plain ◽  
The United States ◽  
The North ◽  
Early Oligocene ◽  
Half Graben ◽  
History Of ◽  
Composition Structure ◽  
Southern Rocky Mountain ◽  
Block Faulting

The Tertiary history of the southern Rocky Mountain Trench is inferred from a study of the distribution, stratigraphy, fabric, lithologic composition, structure, and palynology of the Miocene St. Eugene Formation in southeastern British Columbia.The St. Eugene Formation consists of flood-plain and fan facies and represents the upper part of up to about 1500 m of sediments which accumulated in the proto-Rocky Mountain Trench upon cessation of Laramide deformation and after initiation of extension and block faulting in the eastern Cordillera during Eocene or early Oligocene time. Deep Tertiary basins in the southern Rocky Mountain Trench are bounded on the east and west by high-angle faults parallel to the Trench margins and on the north and south by faults transverse to the trend of the Trench. Block faulting of a half-graben style was probably contemporaneous with sediment deposition, but at least 600 m of displacement on the east boundary fault postdates deposition of the St. Eugene Formation. Although there is no present seismic activity along the Rocky Mountain Trench north of latitude 49°N, Holocene fault scarps and earthquakes in a zone along the Rocky Mountains of the United States attest to the continuation of block faulting south of 49°N.The St. Eugene microflora includes at least 39 genera of ferns, gymnosperms, and anthophytes. Phytogeographic reconstruction based upon the habitats of extant counter-parts indicates floral elements growing on poorly drained lowlands, adjacent slopes, and montane uplands; thus, there was moderate to high relief in southeastern British Columbia during St. Eugene time. The climate apparently was temperate, with warm summers, mild winters, and abundant, uniformly distributed precipitation. This contrasts with the present climate of the southern Rocky Mountain Trench which is semiarid with hot summers and cold winters, and suggests that the mountain barriers which presently restrict cool, moist, Pacific maritime air masses to the coast were lower during the Miocene, or that the polar seas were relatively warm.

Late Quaternary Sediments and Geomorphic History of the Southern Rocky Mountain Trench, British Columbia

1975 ◽  
Vol 12 (4) ◽  
pp. 595-605 ◽  
Author(s):  
John J. Clague
Keyword(s):  
British Columbia ◽  
Short Duration ◽  
Late Quaternary ◽  
Lacustrine Sediments ◽  
Rocky Mountain ◽  
Quaternary Sediments ◽  
Glacier Recession ◽  
History Of ◽  
Cordilleran Ice Sheet ◽  
Southern Rocky Mountain

The southern Rocky Mountain Trench was a major outlet valley of the Cordilleran Ice Sheet. Quaternary sediments underlying the floor of the trench in southeastern British Columbia consist mainly of glacial, glaciofluvial, and glaciolacustrine materials deposited during the Fraser (Pinedale) Glaciation, and fluvial and lacustrine sediments deposited during the preceding interglaciation.Deposits of three stades and two intervening nonglacial intervals are recognized. Interglacial sediments which contain wood dated at 26 800 ± 1000 y B.P. underlie drift of the early stade. During the interval between the early and middle stades, the Rocky Mountain Trench in southeastern British Columbia probably was completely deglaciated, and sediments were deposited in one or more lakes on the floor of the trench. In contrast, glacier recession between the middle and late stades was of short duration and extent; glaciolacustrine sediments were deposited only along the margins of the Rocky Mountain Trench, and apparently residual ice remained in the center of the valley. Final recession of the trunk glacier occurred prior to 10 000 y B.P. with no major halts and without significant stagnation of the terminus.

Sign in / Sign up

Export Citation Format

Share Document