Emergence of the Canadian Rockies and adjacent plains: A comparison of physiography between end-of-Laramide time and the present day

Osborn, Gerald; Stockmal, Glen S.; Haspel, Rebecca

doi:10.1016/j.geomorph.2005.07.032

Cited by 25 publications

(22 citation statements)

References 42 publications

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“…1). The headwaters of these rivers are largely bedrock controlled, flowing along strike (NW-SE) within relatively narrow valleys until they emerge from the mountains and flow north-eastwards down the regional gradient within broader valleys (Osborn et al, 2006). Previous mapping identified complex ice sheet interactions along the mountain front.…”

Section: Regional Settingmentioning

confidence: 99%

Reconstructing the confluence zone between Laurentide and Cordilleran ice sheets along the Rocky Mountain Foothills, south‐west Alberta

Utting

Atkinson

Pawley

et al. 2016

J Quaternary Science

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Landform mapping near the Athabasca valley was fundamental to determining whether or not the Late Wisconsinan Laurentide and Cordilleran Ice Sheets coalesced. In this paper we examine the detailed landform record using new LiDAR digital elevation and hillshade models of the area of confluence and eventual desuturing of these ice sheets. This work reveals an earlier more extensive Cordilleran advance prior to coalescence with the LIS. When the ice sheets coalesced, the flow pattern is dominated by ice flow along the mountain front, with Cordilleran ice flowing out of major trunk valleys but Laurentide ice flowing into the Foothills up smaller valleys. This flow pattern implies that when the ice sheets coalesced the CIS was already waning, or at least was not at its maximum. Deglaciation was interrupted by several re-advances, likely related to the destabilizing effect of proglacial lakes along the ice margin.

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Section: Regional Settingmentioning

confidence: 99%

Reconstructing the confluence zone between Laurentide and Cordilleran ice sheets along the Rocky Mountain Foothills, south‐west Alberta

Utting

Atkinson

Pawley

et al. 2016

J Quaternary Science

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“…The Laramide Orogeny in Canada refers to thin-skinned fold-and-thrust deformation (Figure 2.1) that is Late-Cretaceous to Early-Tertiary in age, and involves cratonic/platformal rocks (Osborn et al, 2006). The Southern Canadian Rockies are commonly divided into the following sub-provinces: Front Ranges, Main Ranges, Western ranges, and Foothills (Bally et al, 1966;North & Henderson, 1954;Osborn et al, 2006). …”

Section: Structural Geology Of the Canadian Rockiesmentioning

confidence: 99%

“…At the end of the Laramide orogeny (~60 Ma), the present Front Ranges were almost or entirely covered with Mesozoic rock, with low-to-moderate local relief and the dominant vegetation resembling that of present Foothills. Due to erosion, the removal of Mesozoic rocks exposed the Paleozoic and Proterozoic rocks that could support the steep and high slopes (Osborn et al, 2006). Evidence from fission-track analysis shows that deformation within the Rocky Mountain Fold and Thrust Belt continued for a few million years, past the 60 Ma age (Kalkreuth & McMechan, 1996).…”

Section: The Front Ranges Of the Canadian Rockiesmentioning

confidence: 99%

“…The Canadian Rocky Mountains were formed by plate tectonic collision and uplift during the Laramide Orogeny (80 to 55 Ma) producing landscapes of high-elevation, yet fairly low relief (Gardner et al, 1983;English & Johnston, 2004;Osborn et al, 2006;Trenhaile, 2010;Hoffman et. al., 2013).…”

Section: Introductionmentioning

confidence: 99%

“…al., 2013). Substantial evidence shows that several kilometers of overburden have been removed from the Canadian Rockies since the end of the Laramide Orogeny (approximately 60 Ma) (Osborn et al, 2006;Trenhaile, 2010). The present-day topography of the Canadian Rockies represents ongoing erosion since the end of the Laramide Orogeny.…”

Section: Introductionmentioning

confidence: 99%

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Controls on Rockfall-Talus Process-Response Systems, Kananaskis, Canadian Rockies

Thapa¹

2017

Geological Society of America Abstracts With Programs

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Rockfall processes are important contributors to hillslope erosion in mountainous regions.Assessment of rockfall activity processes over regional scales has not been widely undertaken, and further assessment about controls of rockfall-talus processes is required.The present study investigates rockfall-talus processes over extended spatiotemporal scales in Kananaskis, Canadian Rockies utilizing aerial photographs, digital elevation models, geologic and paleoclimatic data. An inventory of talus deposits in fifth-order drainage basins was collected for Kananaskis, with rockfall erosion rates of 2.9 mm yr -1 . Resultsshow a strong association of talus with faults and cirques. Although frost cracking is likely an important process leading to rockfall erosion, reconstructed temperature data suggests frost cracking alone is not the major determinant of locations of rockfall activity and talus deposition. Findings of this study provide important information on the contribution and controls of rockfall activity that can be utilized to better understand landscape evolution in mountainous regions.iii

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Postglacial adjustment of steep, low-order drainage basins, Canadian Rocky Mountains

Hoffmann

Müller

Johnson

et al. 2013

J. Geophys. Res. Earth Surf.

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[1] It is generally argued that Pleistocene glaciation results in increased sediment flux in mountain systems. An important, but not well constrained, aspect of Pleistocene glacial erosion is the geomorphic decoupling of cirque basins from main river systems. This study provides a quantitative link between glacier-induced basin morphology, postglacial erosion, and sediment delivery for mountain headwaters (with basin area <10 km 2 ). We analyze the morphology of 57 headwater basins in the Canadian Rockies and establish postglacial sediment budgets for select basins. Notable differences in headwater morphology suggest different degrees of erosion by cirque glaciers, which we classify into headwater basins with either cirque or noncirque morphology. Despite steeper slope gradients in cirque basins, higher-mean postglacial erosion rates in basins with noncirque morphology (0.43-0.6 mm a À1 ) compared to those in cirques (0.19-0.39 mm a À1 ) suggest a more complex relationship between hillslope erosion and slope gradient in calcareous mountain environments than implied by the threshold hillslope concept. Higher values of channel profile concavity and lower channel gradients in cirques imply lower transport capacities and, thus, lower sediment delivery ratios (SDR). These results are supported by (i) postglacial SDR values for cirques and noncirque basins of <15% and >28%, respectively, and (ii) larger fan sizes at outlets of noncirque basins compared to cirques. Although small headwater basins represent the steepest part of mountain environments and erode significant postglacial sediment, the majority of sediment remains in storage under interglacial climatic conditions and does not affect large-scale mountain river systems.

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Emergence of the Canadian Rockies and adjacent plains: A comparison of physiography between end-of-Laramide time and the present day

Cited by 25 publications

References 42 publications

Reconstructing the confluence zone between Laurentide and Cordilleran ice sheets along the Rocky Mountain Foothills, south‐west Alberta

Reconstructing the confluence zone between Laurentide and Cordilleran ice sheets along the Rocky Mountain Foothills, south‐west Alberta

Controls on Rockfall-Talus Process-Response Systems, Kananaskis, Canadian Rockies

Postglacial adjustment of steep, low-order drainage basins, Canadian Rocky Mountains

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