Sackungen at the Aspen Highlands Ski Area, Pitkin County, Colorado

McCalpin, James P.; Irvine, James R.

doi:10.2113/gseegeosci.i.3.277

Cited by 78 publications

(62 citation statements)

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“…The lake-center sediments are also similar to loess mantles found on rock glacier deposits near Mt. Sopris to the north (Birkeland, 1973) and fine-grained, loess-like sediments that accumulated in structural depressions in the Aspen Highlands Ski Area to the southeast (McCalpin and Irvine, 1995). In addition, luminescence signals for most of the lake-center sediment samples collected for dating purposes exhibited consistent and homogeneous properties, which further indicate an eolian, rather than fluvial or alluvial, transport mechanism (Mahan et al, 2014-in this volume).…”

Section: Origin Of Lake-center Sedimentssupporting

confidence: 56%

Geologic setting and stratigraphy of the Ziegler Reservoir fossil site, Snowmass Village, Colorado

et al. 2014

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The geologic setting of the Ziegler Reservoir fossil site is somewhat unusual -the sediments containing the Pleistocene fossils were deposited in a lake on top of a ridge. The lake basin was formed near Snowmass Village, Colorado (USA) when a glacier flowing down Snowmass Creek Valley became thick enough to overtop a low point in the eastern valley wall and entered the head of Brush Creek Valley. When the glacier retreated at about 155-130 ka, near the end of Marine Oxygen Isotope Stage 6, the Brush Creek Valley lobe left behind a moraine that impounded a small alpine lake. The lake was initially~10 m deep and appears to have been highly productive during most of its existence, based on the abundant and exquisitely preserved organic material present in the sediments. Over time, the basin slowly filled with (mostly) eolian sediment such that by~87 ka it contained a marsh or wetland rather than a true lake. Open-water conditions returned briefly between~77 and 55 ka before the impoundment was finally breached to the east, establishing ties with the Brush Creek drainage system and creating an alpine meadow that persisted until historic times.Published by Elsevier Inc. on behalf of University of Washington.

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Section: Origin Of Lake-center Sedimentssupporting

confidence: 56%

Geologic setting and stratigraphy of the Ziegler Reservoir fossil site, Snowmass Village, Colorado

et al. 2014

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“…They typically occur along the flanks of valleys and form by uplift of the valley-side block relative to the mountain-side block. Uphill-facing scarps have been reported from many mountain ranges, e.g., the Rocky Mountains (McCalpin & Irvine 1995), the Coast Mountains of British Columbia (Bovis 1982), Alaska (Radbruch-Hall 1978), the Northern Carpathian Mountains (Mahr & Nemcok 1977), the Pyrenees (Gutiérrez-Santolalla et al 2005) and in Scotland (Jarmann 2006). They were earlier described in the European Alps (Jäckli 1951(Jäckli , 1965 and extensively studied by numerous workers (e.g.…”

Section: Introductionmentioning

confidence: 99%

Composite faults in the Swiss Alps formed by the interplay of tectonics, gravitation and postglacial rebound: an integrated field and modelling study

2008

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Along the flanks of several valleys in the Swiss Alps, well-preserved fault scarps occur between 1900 and 2400 m altitude, which reveal uplift of the valley-side block relative to the mountain-side block. The height of these uphillfacing scarps varies between 0.5 m and more than 10 m along strike of the fault traces, which usually trend parallel to the valley axes. The formation of the scarps is generally attributed either to tectonic movements or gravitational slope instabilities. Here we combine field data and numerical experiments to show that the scarps may be of composite origin, i.e. that tectonic and gravitational processes as well as postglacial differential uplift may have contributed to their formation. Tectonic displacement may occur as the fault scarps run parallel to older tectonic faults. The tectonic component seems, however, to be minor as the studied valleys lack seismic activity. A large gravitational component, which is feasible owing to the steep dip of the schistosity and lithologic boundaries in the studied valleys, is indicated by the uneven morphology of the scarps, which is typical of slope movements. Postglacial differential uplift of the valley floor with respect to the summits provides a third feasible mechanism for scarp formation, as the scarps are postglacial in age and occur on the flanks of valleys that were filled with ice during the last glacial maximum. Finite-element experiments show that postglacial unloading and rebound can initiate slip on steeply dipping pre-existing weak zones and explain part of the observed scarp height. From our field and modelling results we conclude that the formation of uphill-facing scarps is primarily promoted by a steeply dipping schistosity striking parallel to the valley axes and, in addition, by mechanically weaker rocks in the valley with respect to the summits. Our findings imply that the identification of surface expressions related to active faults can be hindered by similar morphologic structures of non-tectonic origin.

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“…Varnes and others, 1989;Clague and Evans, 1994). The relatively subdued appearance of the West Mountain features may be a result of slower rates of slip in the Holocene, as has been documented in recent detailed sackung investigations in Colorado (McCalpin and Irvine, 1995).…”

Section: Sackung Features On West Mountainmentioning

confidence: 85%

“…Some studies suggest that sackung features are directly related to tectonic activity (e.g. Solonenko, 1977;Morton and others, 1989), but many studies relate sackung features to large-scale gravitational spreading of mountainous terrain (Radbruch-Hall and others, 1976;Bovis, 1982;Varnes and others, 1989;Clague and Evans, 1994;McCalpin and Irvine, 1995). The presence of Pinedale-aged cirques (Carrara and Doerner, others, 1983 andCurrey, 1990; data from R.C.…”

Section: Sackung Features On West Mountainmentioning

confidence: 99%

Surficial geology and neotectonics of selected areas of western Idaho and northeastern Oregon

Personius¹

1998

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Sackungen at the Aspen Highlands Ski Area, Pitkin County, Colorado

Cited by 78 publications

References 0 publications

Geologic setting and stratigraphy of the Ziegler Reservoir fossil site, Snowmass Village, Colorado

Geologic setting and stratigraphy of the Ziegler Reservoir fossil site, Snowmass Village, Colorado

Composite faults in the Swiss Alps formed by the interplay of tectonics, gravitation and postglacial rebound: an integrated field and modelling study

Surficial geology and neotectonics of selected areas of western Idaho and northeastern Oregon

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