Eocene paleo-physiography and drainage directions, southern Interior Plateau, British Columbia

2005 ◽  
Vol 42 (2) ◽  
pp. 215-230 ◽  
Author(s):  
Selina Tribe
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Regional Scale ◽  
River Valley ◽  
Coast Mountains ◽  
Base Level ◽  
The North ◽  
Bedrock Geology ◽  
River Valleys ◽  
Early Cenozoic

A map of reconstructed Eocene physiography and drainage directions is presented for the southern Interior Plateau region, British Columbia south of 53°N. Eocene landforms are inferred from the distribution and depositional paleoenvironment of Eocene rocks and from crosscutting relationships between regional-scale geomorphology and bedrock geology of known age. Eocene drainage directions are inferred from physiography, relief, and base level elevations of the sub-Eocene unconformity and the documented distribution, provenance, and paleocurrents of early Cenozoic fluvial sediments. The Eocene landscape of the southern Interior Plateau resembled its modern counterpart, with highlands, plains, and deeply incised drainages, except regional drainage was to the north. An anabranching valley system trending west and northwest from Quesnel and Shuswap Highlands, across the Cariboo Plateau to the Fraser River valley, contained north-flowing streams from Eocene to early Quaternary time. Other valleys dating back at least to Middle Eocene time include the North Thompson valley south of Clearwater, Thompson valley from Kamloops to Spences Bridge, the valley containing Nicola Lake, Bridge River valley, and Okanagan Lake valley. During the early Cenozoic, highlands existed where the Coast Mountains are today. Southward drainage along the modern Fraser, Chilcotin, and Thompson River valleys was established after the Late Miocene.

scholarly journals Pleistocene horses (genus Equus) in the central Balkans

2003 ◽  
pp. 55-75 ◽  
Author(s):  
Ann Forsten ◽  
Vesna Dimitrijevic
Keyword(s):  
Late Pleistocene ◽  
River Valley ◽  
Middle Pleistocene ◽  
Mountainous Area ◽  
Migration Routes ◽  
Northern Greece ◽  
The North ◽  
Time Period ◽  
Morava River ◽  
River Valleys

A review of the fossil horses of the genus Equus from the central Balkans, a mountainous area comprising Serbia and Montenegro, is presented in this paper. The time period covered by the finds is from the late Early to and including the Late Pleistocene, but the record is not complete: the dated finds are Late Pleistocene in age, while Early and Middle Pleistocene are poorly represented. The horses found resemble those from neighbouring countries from the same time period, probably showing the importance of river valleys as migration routes. The Morava River valley runs in a roughly south-to-north direction, connecting, via the Danube and Tisa River valleys the Hungarian Pannonian Plain in the north with northern Greece in the south, via the Vardar River valley in Macedonia. In Pleistocene, large mammals, including horses, probably used this route for dispersal.

Taxonomy, phylogeny, and paleoecology of Eoseira wilsonii gen. et sp. nov., a Middle Eocene diatom (Bacillariophyceae: Aulacoseiraceae) from lake sediments at Horsefly, British Columbia, Canada

2005 ◽  
Vol 42 (2) ◽  
pp. 243-257 ◽  
Author(s):  
Alexander P Wolfe ◽  
Mark B Edlund
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Life Strategy ◽  
Centric Diatom ◽  
Evolutionary Trajectory ◽  
The Family ◽  
Freshwater Diatoms ◽  
Marine Realm ◽  
Diatom Genus ◽  
Early Cenozoic

A new centric diatom genus is described from laminated freshwater sediments of Middle Eocene age near Horsefly, British Columbia, Canada. This diatom, Eoseira wilsonii gen. et sp. nov., grew in filaments that constitute dense monospecific sub-horizons within the white couplets that represent summer deposition in the varved sequence. Although Eoseira clearly belongs within the Family Aulacoseiraceae, several features distinguish its valve structure from Aulacoseira. Gigantism of spines and the lack of geometric relationships between spine position and mantle areolae are the most conspicuous features of the genus. Eoseira is among the oldest freshwater diatoms known and one of relatively few extinct freshwater genera. In addition to serving as a potential biostratigraphic marker, Eoseira is a cornerstone to undertanding the evolutionary trajectory of the Aulacoseiraceae, likely the oldest family of freshwater diatoms. As such, it refines our understanding of early radiations from the marine realm in western North America. Furthermore, paleoecological inferences based on Eoseira life strategy pertain directly to limnological conditions during early Cenozoic hot-house conditions.

scholarly journals Observations on the May 2019 Joffre Peak landslides, British Columbia

Landslides ◽  
2020 ◽  
Vol 17 (4) ◽  
pp. 913-930 ◽  
Author(s):  
Pierre Friele ◽  
Tom H. Millard ◽  
Andrew Mitchell ◽  
Kate E. Allstadt ◽  
Brian Menounos ◽  
...  
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Seismic Analysis ◽  
Rock Avalanche ◽  
Permafrost Degradation ◽  
Depth Estimate ◽  
Coast Mountains ◽  
Conditioning Factors ◽  
The North ◽  
Debris Flood

AbstractTwo catastrophic landslides occurred in quick succession on 13 and 16 May 2019, from the north face of Joffre Peak, Cerise Creek, southern Coast Mountains, British Columbia. With headscarps at 2560 m and 2690 m elevation, both began as rock avalanches, rapidly transforming into debris flows along middle Cerise Creek, and finally into debris floods affecting the fan. Beyond the fan margin, a flood surge on Cayoosh Creek reached bankfull and attenuated rapidly downstream; only fine sediment reached Duffey Lake. The toe of the main debris flow deposit reached 4 km from the headscarp, with a travel angle of 0.28, while the debris flood phase reached the fan margin 5.9 km downstream, with a travel angle of 0.22. Photogrammetry indicates the source volume of each event is 2–3 Mm3, with combined volume of 5 Mm3. Lidar differencing, used to assess deposit volume, yielded a similar total result, although error in the depth estimate introduced large volume error masking the expected increase due to dilation and entrainment. The average velocity of the rock avalanche-debris flow phases, from seismic analysis, was ~ 25–30 m/s, and the velocity of the 16 May debris flood on the upper fan, from super-elevation and boulder sizes, was 5–10 m/s. The volume of debris deposited on the fan was ~ 104 m3, 2 orders of magnitude less than the avalanche/debris flow phases. Progressive glacier retreat and permafrost degradation were likely the conditioning factors; precursor rockfall activity was noted at least ~6 months previous; thus, the mountain was primed to fail. The 13 May landslide was apparently triggered by rapid snowmelt, with debuttressing triggering the 16 May event.

Coquitlam Drift: a pre-Vashon Fraser glacial formation in the Fraser Lowland, British Columbia

1981 ◽  
Vol 18 (9) ◽  
pp. 1443-1451 ◽  
Author(s):  
Stephen R. Hicock ◽  
John E. Armstrong
Keyword(s):  
British Columbia ◽  
Glacial Maximum ◽  
Cascade Mountains ◽  
Short Pulses ◽  
Coast Mountains ◽  
The North ◽  
Glaciomarine Sediments

Coquitlam Drift is formally defined and stratotypes established for it in the Coquitlam – Port Moody area, B.C. It is a Pleistocene formation consisting of till, glaciofluvial, ice-contact, and glaciomarine sediments deposited between 21 700 and 18 700 years BP, during the Fraser Glaciation (late Wisconsin) and prior to the main Vashon glacial maximum at about 14 500 years BP. The drift was deposited in short pulses by valley and piedmont glaciers fluctuating into the Fraser Lowland from the Coast Mountains to the north and Cascade Mountains to the east.

The Archaeological Delineation of a Cultural Boundary in Papagueria

1955 ◽  
Vol 20 (4Part1) ◽  
pp. 367-374 ◽  
Author(s):  
Paul H. Ezell
Keyword(s):  
Gulf Of California ◽  
Colorado River ◽  
River Valley ◽  
Historical Sources ◽  
Gila River ◽  
The North ◽  
Ethnic Boundary ◽  
Cultural Boundary ◽  
Imaginary Line ◽  
River Valleys

The area dealt with in this report is that portion of northwestern Sonora and southwestern Arizona bounded on the southwest by the Gulf of California, on the west by the Colorado River valley below the junction of the Gila River, on the north by the Gila River valley, and on the east by an imaginary line from the vicinity of Gila Bend south along the western edge of the Papago Reservation and thence southwest to the mouth of the Sonoyta River on the Gulf of California (Fig. 106). Within this area Sauer has suggested a boundary between the Piman-speaking people of southern Arizona and northern Sonora, and the Yuman-speaking tribes of the lower Colorado and Gila River valleys, based on linguistic affiliations described in early historical sources (Sauer 1934, map). On archaeological evidence Gifford has suggested that the locality between Punta La Cholla and the mouth of the Sonoyta River represented a point on an ethnic boundary (Gifford 1946: 221).

Late Pleistocene stratigraphy and chronology of lower Chehalis River valley, southwestern British Columbia: evidence for a restricted Coquitlam Stade

2004 ◽  
Vol 41 (7) ◽  
pp. 881-895 ◽  
Author(s):  
Brent C Ward ◽  
Bruce Thomson
Keyword(s):  
British Columbia ◽  
Late Pleistocene ◽  
River Valley ◽  
Glacial Lakes ◽  
Coast Mountains ◽  
Source Areas ◽  
Definitive Evidence

Sediments in lower Chehalis valley span middle Wisconsin (Olympia nonglacial interval) to Holocene time. Sediments are divided into six units with chronological control provided by 14 new radiocarbon ages. Fluvial gravel spans the transition from the late Olympia nonglacial interval to the early Fraser Glaciation. Glaciolacustrine sedimentation represents the first definitive glacial activity in the valley and indicates that Vashon ice in the Fraser Lowland blocked the mouth of the Chehalis valley at ca. 18–17 ka BP. Ice then flowed down the Chehalis valley. The Chehalis valley deglaciated while ice persisted in the Fraser Lowland, forming another lake. After this lake drained, terraces and fans formed. This style of glaciation–deglaciation is typical of many watersheds peripheral to the Fraser Lowland in that local valley ice was slightly out of phase with ice in the lowland. This resulted in glacial lakes forming during both advance and retreat phases. However, in contrast to watersheds in the northwestern Fraser Lowland, no definitive evidence of a Coquitlam ice advance was found within the Chehalis valley. Although glaciers in the area were likely active and advancing, data from the Chehalis valley indicates that they were not as extensive as previously thought. Since ice source areas in the northeastern Fraser Lowland are in the leeward area of the Coast Mountains, it is suggested that lower precipitation resulted in limited glacier activity there during the Coquitlam Stade.

The record of jökulhlaups from Summit Lake, northwestern British Columbia

1993 ◽  
Vol 30 (3) ◽  
pp. 499-508 ◽  
Author(s):  
William H. Mathews ◽  
John J. Clague
Keyword(s):  
British Columbia ◽  
Water Level ◽  
River Valley ◽  
Water Level Fluctuations ◽  
Salmon River ◽  
The Road ◽  
The North ◽  
Large Numbers ◽  
Dammed Lake ◽  
Effective Seal

Summit Lake, which is impounded by Salmon Glacier, is the largest self-draining, ice-dammed lake in Canada. Until 1961, it contained few icebergs and was stable, overflowing to the north into me Bowser River valley. The first jökulhlaup occurred in December 1961, after a lengthy period of thinning and retreat of Salmon Glacier, when a subglacial runnel developed in the weakened ice dam, allowing the lake to drain suddenly. This flood and two others in 1965 and 1967 caused major damage to the road system in the Salmon River valley south of the lake. Since 1965, with three exceptions, Summit Lake has drained annually; minor floods along Salmon River in 1966, 1969, and 1973 may record partial drainings of the lake, although other explanations are possible. Jökulhlaups in recent years have been smaller and have occurred earlier in the year than most of the early floods. Rapid water-level fluctuations associated with the annual emptying and refilling of Summit Lake have generated large numbers of icebergs, derived from the Salmon Glacier dam; these icebergs presently choke the surface of the lake. The present jökulhlaup cycle is likely to continue either until the glacier readvances or until it retreats to the point that it no longer forms an effective seal.

Interpretation of structures in the southeastern Nechako Basin, British Columbia, from seismic reflection, well log, and potential field data1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.2Geological Survey of Canada Contribution 20100002.

2011 ◽  
Vol 48 (6) ◽  
pp. 1000-1020 ◽  
Author(s):  
Nathan Hayward ◽  
Andrew J. Calvert
Keyword(s):  
British Columbia ◽  
Potential Field ◽  
Seismic Reflection ◽  
Middle Eocene ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Late Eocene ◽  
Strike Slip ◽  
Potential Field Data ◽  
The North

The structure and stratigraphy of the southeast Nechako Basin, which are poorly understood primarily because of substantial volcanic cover, are investigated in an analysis of seismic reflection, well, and potential field data. Formation and development of the SE Nechako Basin resulted in sub-basins containing Cretaceous and Eocene rocks. Interpretation reveals that dextral transtension in the Early to Middle Eocene created NNW-trending, en echelon, strike-slip faults linked by pull-apart basins, which locally contain a thickness of Eocene volcaniclastic rocks of >3 km. This structural pattern is consistent with regional observations that suggest the transfer of slip from the Yalakom fault to the north via a series of en echelon strike-slip faults. In the Middle to Late Eocene, faults associated with a change in the direction of stress, echoed by the north-trending right-lateral Fraser fault, reactivated and cut earlier structures. A simple model agrees with local observations, that northeast-directed compression was subparallel to the relic Cretaceous grain. Cretaceous rocks are discontinuous throughout the basin and may be remnants of a broader basin, or a number of contemporaneous basins, formed in a regional transpressional tectonic setting that caused northeast-directed thrusting along the eastern side of the Coast Plutonic Complex. Results suggest that thrusting affected most of the SE Nechako Basin, as observed across the Intermontane Belt to the northwest and southeast. The pattern of deposition of Neogene volcanic rocks of the Chilcotin Group was in part controlled by the Eocene structural grain, but we find no evidence of Neogene deformation.

Age of the Bowen Island Group, southwestern Coast Mountains, British Columbia

1990 ◽  
Vol 27 (11) ◽  
pp. 1456-1461 ◽  
Author(s):  
R. M. Friedman ◽  
J. W. H. Monger ◽  
H. W. Tipper
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Volcanic Rocks ◽  
Sedimentary Facies ◽  
Lower Jurassic ◽  
Coast Mountains ◽  
The North ◽  
Metavolcanic Rocks ◽  
Lake Formation ◽  
Island Group

A new U–Pb date of [Formula: see text] for foliated felsic metavolcanic rocks of the Bowen Island Group, from Mount Elphinstone in the southwesternmost Coast Mountains of British Columbia, indicates that there the age of this hitherto undated unit is early Middle Jurassic. These rocks grade along strike to the north-northwest into a more sedimentary facies, which north of Jervis Inlet contains a probable Sinemurian (Lower Jurassic) ammonite. The Bowen Island Group thus appears to include Lower and Middle Jurassic rocks and to be coeval in part with volcanic rocks of the Bonanza Formation on Vancouver Island to the west and the Harrison Lake Formation within the central Coast Mountains 75 km to the east.

Out-of-phase Holocene terraces in part of the North Saskatchewan River basin, Alberta

1988 ◽  
Vol 25 (3) ◽  
pp. 454-464 ◽  
Author(s):  
Bruce Rains ◽  
James Welch
Keyword(s):  
River Valley ◽  
Alluvial Terrace ◽  
Base Level ◽  
The North ◽  
Alluvial Sediment ◽  
Main River ◽  
Alluvial Terraces ◽  
Local Base ◽  
Geochronological Evidence ◽  
Small Tributary

This study focuses on alluvial terraces in part of the North Saskatchewan River valley, near Edmonton, and in the small tributary valleys of Whitemud and Strawberry creeks. The characteristic terrace morphologies and alluvial sediment sequences are briefly described, but most importantly, the deposits are radiocarbon dated for many sites. Twenty-seven new 14C dates on bone, wood, charcoal, and shell materials, along with previously reported dates, provide the chronological framework for the study. Occurrences of the Mazama ash marker bed in terrace alluvium offer additional geochronological evidence. The small tributary valleys have clearly developed in an out-of-phase manner relative to the main river valley, which acts as their local base level. Despite the comparatively abundant geochronological evidence described here, the explanation of alluvial terrace development, in terms of predominant causal factors, remains tantalizingly elusive.

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