Influence of a glacial buzzsaw on the height and morphology of the Cascade Range in central Washington State, USA

Mitchell, Sara Gran; Montgomery, David R.

doi:10.1016/j.yqres.2005.08.018

Cited by 195 publications

(186 citation statements)

References 46 publications

Supporting

Mentioning

179

Contrasting

Order By: Relevance

“…The physical form of a glaciated valley is the product of the interaction between the effectiveness of erosion by glacier ice and the resistance to erosion and the structure of the country rock in which the glaciated valley resides. There are three broad aspects of glaciated valley morphometry that have been the focus of research: rates of sediment evacuation and relief development (Small and Anderson, 1998;Whipple et al, 1999;Brocklehurst and Whipple, 2002, Montgomery, 2002b, Koppes and Hallet, 2006Mitchell and Montgomery, 2006;Oskin and Burbank, 2005), development of the longitudinal profile (e.g. MacGregor et al, 2000), and development of cross-sectional form (e.g.…”

Section: Introductionmentioning

confidence: 99%

Relative size of fluvial and glaciated valleys in central Idaho

2008

Self Cite

View full text Add to dashboard Cite

Quantitative comparisons of the morphometry of glaciated and fluvial valleys in central Idaho were used to investigate the differences in valley relief and width in otherwise similar geologic and geomorphic settings. The local relief, width, and crosssectional area of valleys were measured using GIS software to extract information from USGS digital elevation models. Hillslope gradients were also measured using GIS software. Power-law relationships for local valley relief, width, and cross-sectional area as a function of drainage area were developed. Local valley relief in glaciated valleys relates to drainage area with a power-law exponent similar to fluvial valleys, but glaciated valleys are deeper for a given drainage area. Local valley width in glaciated valleys is greater than in fluvial valleys, but the exponent of the power-law relationship to drainage area is similar in both valley types. Local valley cross-sectional area in glaciated valleys increases with drainage area with a power-law exponent similar to fluvial valleys, however, glacial valleys have roughly 80% greater cross-sectional area. Steep valley walls in glaciated basins increase the potential for bedrock landsliding relative to fluvial basins. Both the Olympic Mountains of Washington and valleys in central Idaho show relationships in which glaciated valleys are up to 30% deeper than fluvial valleys despite differences in lithology, tectonic setting, and climate.

show abstract

Section: Introductionmentioning

confidence: 99%

Relative size of fluvial and glaciated valleys in central Idaho

2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, in the tectonically active Himalaya Gabet et al (2004) document that a doubling of annual rainfall from 2000 to 4000 mm results in a 33 %-decrease in total relief. Conversely, glacial erosion appears to be one of the main relief-generating processes focusing the removal of material near the peaks, and thereby maintaining steep topography above the equilibrium-line altitude (ELA) and limiting range height (Hallet et al, 1996;Brozovic et al, 1997;Small and Anderson, 1998;Tomkin and Braun, 2002;Mitchell and Montgomery, 2006). However, the role of climateinduced relief production has been challenged and it has been argued that active mountain belts are already characterized by threshold relief Montgomery and Brandon, 2002).…”

mentioning

confidence: 99%

The topographic imprint of a transient climate episode: the western Andean flank between 15·5° and 41·5°S

Rehak

Bookhagen

Strecker

et al. 2010

Earth Surf Processes Landf

View full text Add to dashboard Cite

Mountain-range topography is determined by the complex interplay between tectonics and climate. However, often it is not clear to what extent climate forces topographic evolution and how past climatic episodes are reflected in relief. The Andes are a tectonically active mountain belt encompassing various climatic zones with pronounced differences in rainfall and glacier extent under similar plate-boundary conditions. In the Central to South-Western Andes climatic zones range from hyperarid desert with mean annual rainfall of 5 mm/a (22.5°S) to year-round humidity with 2500 mm/a (40°S). The Andes thus provide a unique setting for investigating the relationship between climate and topography. We present the analysis of 120 catchments along the western Andean watersheds between 15.5° and 41.5°S, which is based on SRTMV3-90m data and the new medium-resolution rainfall (TRMM) dataset. For each basin, we extracted geometry, relief, and climate parameters to test whether Andean topography shows a climatic imprint and to analyze how climate influences relief. Our data document that elevation and relief decrease with increasing rainfall and descending snowline elevation. Furthermore, we show that local relief reaches high values of 750 m in a zone between 28° to 35°S. During Pleistocene glacial stages this region was affected by the northward shifting southern hemisphere Westerlies, which provided moisture for valley-glacier formation and extended glacial coverage as well as glacial erosion. In contrast, the southern regions between 35° to 40°S receive higher rainfall and have a lower local relief of 200 m, probably related to an increased drainage density. We distinguish two different, climatically-controlled mechanisms shaping topography: (1) fluvial erosion by prolonged channel-hillslope coupling, which smoothes relief, and (2) erosion by valley glaciers that generates relief. Finally, our results suggests that the catchment-scale relief of the Andes between 28° to 35°S is characterized by a pronounced transient component reflecting past climatic conditions.

show abstract

“…5B). This latter scenario is particularly relevant as glacial occupation of mountain ranges increases rates of erosion (denudation), generally reducing the elevation of accumulation areas (see Brozović et al, 1997;Whipple et al, 1999;Tomkin, 2003;Mitchell and Montgomery, 2006;Egholm et al, 2009). Thus, where the erosion of upland topography is efficient, and outpaces uplift, glaciers may become smaller over successive glacial cycles (Kaplan et al, 2009).…”

Section: Ice Extent and Evolving Upland Topographymentioning

confidence: 99%

A review of topographic controls on moraine distribution

2014

View full text Add to dashboard Cite

Ice-marginal moraines are often used to reconstruct the dimensions of former ice masses, which are then used as proxies for palaeoclimate. This approach relies on the assumption that the distribution of moraines in the modern landscape is an accurate reflection of former ice margin positions during climatically controlled periods of ice margin stability. However, the validity of this assumption is open to question, as a number of additional, nonclimatic factors are known to influence moraine distribution. This review considers the role played by topography in this process, with specific focus on moraine formation, preservation, and ease of identification (topoclimatic controls are not considered). Published literature indicates that the importance of topography in regulating moraine distribution varies spatially, temporally, and as a function of the ice mass type responsible for moraine deposition. In particular, in the case of ice sheets and ice caps ( > 1000 km 2 ), one potentially important topographic control on where in a landscape moraines are deposited is erosional feedback, whereby subglacial erosion causes ice masses to become less extensive over successive glacial cycles. For the marine-terminating outlets of such ice masses, fjord geometry also exerts a strong control on where moraines are deposited, promoting their deposition in proximity to valley narrowings, bends, bifurcations, where basins are shallow, and/or in the vicinity of topographic bumps. Moraines formed at the margins of ice sheets and ice caps are likely to be large and readily identifiable in the modern landscape. In the case of icefields and valley glaciers (10-1000 km 2 ), erosional feedback may well play some role in regulating where moraines are deposited, but other factors, including variations in accumulation area topography and the propensity for moraines to form at topographic pinning points, are also likely to be important. This is particularly relevant where land-terminating glaciers extend into piedmont zones (unconfined plains, adjacent to mountain ranges) where large and readily identifiable moraines can be deposited. In the case of cirque glaciers (< 10 km 2 ), erosional feedback is less important, but factors such as topographic controls on the accumulation of redistributed snow and ice and the availability of surface debris, regulate glacier dimensions and thereby determine where moraines are deposited. In such cases, moraines are likely to be small and particularly susceptible to post-depositional modification, sometimes making them difficult to identify in the modern landscape. Based on this review, we suggest that, despite often being difficult to identify, quantify, and mitigate, topographic controls on moraine distribution should be explicitly considered when reconstructing the dimensions of palaeoglaciers and that moraines should be judiciously chosen before being used as indirect proxies for palaeoclimate (i.e., palaeoclimatic inferences should only be drawn from moraines when topographic controls on mora...

show abstract

Influence of a glacial buzzsaw on the height and morphology of the Cascade Range in central Washington State, USA

Cited by 195 publications

References 46 publications

Relative size of fluvial and glaciated valleys in central Idaho

Relative size of fluvial and glaciated valleys in central Idaho

The topographic imprint of a transient climate episode: the western Andean flank between 15·5° and 41·5°S

A review of topographic controls on moraine distribution

Contact Info

Product

Resources

About