On the Development of Transverse Ridges on Rock Glaciers

Loewenherz, Deborah S.; Lawrence, C.J.; Weaver, Richard L.

doi:10.3189/s002214300000931x

Cited by 13 publications

(15 citation statements)

References 37 publications

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“…Unfortunately, the mechanism of formation for the surface ridges is poorly understood for terrestrial glaciers, so any extrapolation to Mars is difficult. The present literature suggests that surface ridge and furrow patterns may be related to external factors (e.g., debris input, climate changes that affect mass balance or ice velocity), internal factors (e.g., internal structure, thrusting or folding within the ice), or some combination of these factors [Loewenherz et al, 1989;Kaab and Weber, 2004]. On the basis of age estimates and measured flow rates for the glaciers within Mullins and Friedman Valley, we suggest that the surface ridges could be forming due to orbitally driven glacial cycles influencing external factors (temperature increases, ice velocity increases, accumulation increases, etc.)…”

Section: Terrestrial Analogsmentioning

confidence: 97%

Recent glaciation at high elevations on Arsia Mons, Mars: Implications for the formation and evolution of large tropical mountain glaciers

Shean¹,

Head²,

Fastook³

et al. 2007

J. Geophys. Res.

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[1] The $166,000 km 2 fan-shaped deposit at Arsia Mons contains three characteristic facies (ridged, knobby, and smooth), which are interpreted as the depositional remains of a cold-based glacier that was present on the west-northwestern flanks in the Late Amazonian period of Mars history. Here, we consider several high-elevation graben on the western flank of Arsia Mons that are interpreted as the source regions for late-stage, cold-based glaciers that overflowed graben walls, advanced tens to hundreds of kilometers downslope, experienced subsequent retreat, and left distinctive depositional features similar to those associated with cold-based glaciers in the Dry Valleys of Antarctica. These new observations provide additional support for a cold-based glacial interpretation of the Tharsis Montes fan-shaped deposits. Morphological evidence suggests that the largest of these graben was the primary source region for the most proximal smooth facies lobes at Arsia Mons, and map-plane ice sheet reconstructions are consistent with these observations. This relationship has significant implications for the relative ages of the individual facies within the fan-shaped deposit, including the possibility that the smooth facies represents several distinct phases of glaciation. The high relief and large elevation differences between the upslope and downslope walls of these graben appear to be critical factors for ice accumulation and the generation/collection of rockfall within glacial accumulation zones. We suggest that rockfall was the dominant process responsible for debris-cover formation on the glaciers sourced within these graben and consider the implications for the entire Arsia fan-shaped deposit. New crater count data suggest that the fill material in the large Arsia graben formed within the past $100 Myr (model age of $65 Ma). Taken together, these new observations provide additional evidence for several periods of Late Amazonian climate change on Mars within the past few 100 Myr resulting in episodes of tropical mountain glaciation. Finally, MOLA topography reveals that several lobate features interpreted as remnant debris-covered ice from the most recent phase of glaciation are presently hundreds of meters thick, suggesting the possibility of long-term, near-surface water ice survival in the equatorial regions of Mars.

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Section: Terrestrial Analogsmentioning

confidence: 97%

Recent glaciation at high elevations on Arsia Mons, Mars: Implications for the formation and evolution of large tropical mountain glaciers

Shean¹,

Head²,

Fastook³

et al. 2007

J. Geophys. Res.

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“…They commonly display steep fronts and transverse surface ridges, possibly the product of differential movement of discrete layers of debris (Loewenherz et al, 1989). The origin of rock glaciers has been a particularly contentious issue in mountain geomorphological research, the traditional view being that these features are periglacial forms with movement explained via a model of creeping permafrost (Barsch, 1978(Barsch, , 1988(Barsch, , 1996Haeberli, 1985).…”

Section: Rock Glacier Genesismentioning

confidence: 99%

Relict rock glaciers as indicators of Mediterranean palaeoclimate during the Last Glacial Maximum (Late Würmian) in northwest Greece

Hughes

Gibbard

Woodward

2003

J Quaternary Science

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Relict rock glaciers have been identified and mapped in the high cirques of Mount Tymphi, in the Pindus mountains of northwest Greece. They are periglacial forms and represent the most recent cold-stage landforms in an area that displays widespread evidence of Pleistocene glaciation. It is likely that these features formed during the Last Glacial Maximum (Late Würmian) as talus rock glaciers, and beneath small cirque glaciers as debris rock glaciers. Comparisons with modern rock glacier-climate relationships suggests mean annual temperatures of ca. 8-9°C lower than present at their time of formation. This temperature reconstruction is in good agreement with recent palaeoclimatic reconstructions for the northern Mediterranean based on a general circulation model. Moreover, as rock glaciers are typical of cold and relatively dry mountain regions, their presence is consistent with palaeobotanical and lake-level data suggesting a cold and relatively dry climate for the Last Glacial Maximum in Greece. However, the presence of small cirque glaciers above some rock glaciers suggests that although precipitation must have been low enough to preclude glacier extension down to lower altitudes, it was not so low as to inhibit glacier formation entirely.

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“…Rock glaciers in Ferintosh Creek display two distinct forms; single lobes, consisting of steep frontal slopes and surficial ridge-andfurrow topography; and double lobes, consisting of an upper (younger) lobe overriding a lower (older) lobe. Both lobes have steep frontal slopes, which are morphologically distinct from surface ridges and furrows of a flow-deformational origin (Loewenherz et a/. 1989).…”

Section: Morphology Of the Rock Glaciersmentioning

confidence: 99%

“…Individual major lateral ridges splay downslope as they bend to become multiple transverse ridges. Such morphology typifies compressive flow zones in rock glaciers (Potter, 1972;Washburn, 1979;Loewenherz et a/., 1989).…”

Section: Morphology Of the Rock Glaciersmentioning

confidence: 99%

On the sensitivity of Holocene talus‐derived rock glaciers to climate change in the Ben Ohau Range, New Zealand

Kirkbride

Brazier

1995

J Quaternary Science

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Kirkbride, M. and Brazier, V. 1995. On the sensitivity of Holocene talus-derived rock glaciers to climate change in the Ben Ohau Range, New Zealand. lournal ABSTRACT: The morphology and surface ages of talus-derived rock glaciers are investigated to establish the timing of rock glacier formation in the central Southern Alps. Samples of rock weathering rinds show that all rock glaciers studied were formed during the Neoglacial period, but differences exist between sites in the number of new rock glacier lobes formed by Holocene climatic fluctuations. A qualitative conceptual model is proposed to explain rock glacier formation in terms of two thresholds. An external threshold relates to the presence of a cool climate capable of allowing internal ice to form within talus slopes. An internal threshold relates to the presence Journal of QJaternary Science of sufficiently thick talus at a site to generate a shear stress capable of overcoming internal friction within the taludice mass. The model produces a non-steady-state response to explain why unmodified talus, single-lobed and double-lobed rock glaciers developed at adjacent sites under the same climatic regime. Individual landforms have different sensitivities to formation, which depend partly on the previous history of talus accumulation and rock glacier activity at a site. The model demonstrates how successive cool climate periods may be fully represented by rock glacier lobes at sensitive sites but under-represented at insensitive sites. Sensitivity (and therefore climatic representativeness) is favoured by high rates of debris supply. By implication, the timing of formation of rock glacier lobes in regions of prolonged cool climate and low debris production is less likely to correspond to the timing of climatic cooling and more likely to follow the 'rules' of deterministic chaos.

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On the Development of Transverse Ridges on Rock Glaciers

Cited by 13 publications

References 37 publications

Recent glaciation at high elevations on Arsia Mons, Mars: Implications for the formation and evolution of large tropical mountain glaciers

Recent glaciation at high elevations on Arsia Mons, Mars: Implications for the formation and evolution of large tropical mountain glaciers

Relict rock glaciers as indicators of Mediterranean palaeoclimate during the Last Glacial Maximum (Late Würmian) in northwest Greece

On the sensitivity of Holocene talus‐derived rock glaciers to climate change in the Ben Ohau Range, New Zealand

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