Impact Landforms Research Articles

Progress and prospects for research on Martian topographic features and typical landform identification

The study of Martian surface topography is important for understanding the geological evolution of Mars and revealing the spatial differentiation of the Martian landscape. Identifying typical landform units is a fundamental task when studying the origin and evolution of Mars and provides important information for landing on and exploring Mars, as well as estimating the age of the Martian surface and inferring the evolution of the Earth’s environment. In this paper, we first investigate Mars exploration, data acquisition and mapping, and the classification methods of Martian landforms. Then, the identification of several typical Martian landform types, such as aeolian landforms, fluvial landforms, and impact landforms, is shown in detail. Finally, the prospects of Mars data acquisition, landform mapping, and the construction and identification of the Martian landform classification system are presented. The construction of the Martian landform classification system and the identification of typical Martian landforms using deep learning are important development directions in planetary science.

Ice‐avalanche impact landforms: the event in 2003 at the glacier nördliches bockkarkees, hohe tauern range, austria

Kellerer‐Pirklbauer, A., Slupetzky, H. and Avian, M., 2012. Ice‐avalanche impact landforms: the event in 2003 at the glacier Nördliches Bockkarkees, Hohe Tauern Range, Austria. Geografiska Annaler: Series A, Physical Geography, 94, 97–115. doi:10.1111/j.1468‐0459.2011.00446.xABSTRACTThe hanging glacier Nördliches Bockkarkees (47°07′21″N; 12°44′00″E) represents the only Austrian glacier that formed large and hazardous ice avalanches over the last decades. Only one major ice avalanche was released between August 1993 and July 2011 underlying the rareness of such large ice avalanches in the Austrian Alps. The ice avalanche happened on 26 June 2003 and was very unusual for two reasons: First, the ice avalanche occurred suddenly without major signs of glacier instabilities even a few days before the event. Second, the ice avalanche was released very early in the season. Ice and debris with a volume of 300-000m3 avalanched over a vertical distance of 1200 m. The main deposits with a volume of 250-000m3 and a debris content of 10% formed a flat avalanche cone in the Käfer Valley covering 82-000m2. This paper focuses on geomorphic and glaciological field measurements and observations at and below the ice avalanche deposit and its vicinity after the event. Studies were made (a) at the deposited material itself, (b) at the reshaped land surface below the deposit after ice melt, (c) at the front and margin of the deposit, and (d) outside the deposit. Our study reveals different types of ice‐avalanche impact landforms comparable to landforms caused by snow avalanches. It is shown that ice avalanches charged with debris at the Nördliches Bockkarkees are important in forming and reshaping erosional and depositional landforms along the track. However, the conservation potential of these landforms is low.

Geomorphology of snow avalanche impact landforms in the southern Canadian Cordillera

Snow avalanche impact landforms (SAILs) are typically elliptical‐shaped depressions bounded by an arcuate ridge located at the base of avalanche paths. The geomorphology of these features is controlled by the topography of the avalanche path, the availability of unconsolidated debris in the impact area and the ability of the avalanche impacts to displace the available debris in the direction of avalanche flow. Ground‐based snow avalanches move debris by bulldozing, and airborne snow avalanches move sediment by excavation on impact.This paper reports on the geomorphology, and surface age and stability of three SAILs in the southern Canadian Cordillera. Dendrochronology and lichenometry were used to date geomorphic activity at the sites. Evidence of present SAIL stability suggests they result from episodic, high‐magnitude avalanche impact events over many hundreds of years. All three landforms share common morphologies: a water‐filled bowl‐shaped depression distally bounded by an arcuate ridge‐oriented transverse to the avalanche path. Despite sharing many attributes, field investigations revealed that the origin of each SAIL was a function of the local variations in snow avalanche path topography and availability of unconsolidated debris in the impact area. The snow avalanche path associated with the Blackhorn site has a gentle gradient, which suggests that this SAIL is a result of ground‐based avalanches. The SAIL at Spoon Lake appears to be a consequence of a resistant geologic feature that focuses snow avalanches in the impact area and results in explosive excavation. The morphology of the snow avalanche track at Peyto Lake causes large snow avalanches to become airborne prior to impacting and excavating an impact pool. All three SAILs examined in this paper are historically persistent landforms and these observations support previous findings indicating that SAILs require hundreds of years to develop.

Snow‐avalanche impact landforms, deposits and effects at urdvatnet, southern norway: implications for avalanche style and process

.An unusual assemblage of landforms and deposits is described from upper Norangsdalen, Sunnmøre region, southern Norway, and interpreted as the product of snow‐avalanche events that vary in magnitude, frequency and debris content. An avalanche impact plunge pool, proximal scar and distal mound are associated with a coarse gravel deposit covering part of the valley floor. Landforms in this debris spread include gravel ridges, boulder lines, beaded ridges, fine sediment banked against and covering large boulders, and gravel clumps. Many of these landforms are aligned, indicating across‐valley transport radiating from the plunge pool. Features were mapped in the field and samples analysed for grain size and heavy‐mineral content. The debris spread is attributed to deposition by high‐energy, debris‐rich snow‐avalanche events that collect debris from large areas of the valley side, lower slopes and plunge pool. Aligned landforms develop through sediment transport in a basal shear zone, and randomly distributed gravel clumps represent melt pits following debris transport in the avalanche body. Air displacement ahead of larger avalanches is thought to have felled and tilted trees on the lower slopes of the distal valley side. Approximate ages of damaged trees allowed estimation of the frequency of snow‐avalanche events: (1) small, frequent events (several per annum) carry debris to the lower valley slopes and the plunge pool; (2) moderate events with an annual to decadal frequency maintain the pool–scar–mound complex; and (3) large, debris‐rich events with a decadal to centennial frequency add material to the debris spread.

‘Protalus ramparts’ on Navajo Mountain, Utah, USA: reinterpretation as blockslope-sourced rock glaciers

Transverse ridges crossing broad lobes of coarse debris on a structural bench at ∼2600–2750 m on Navajo Mountain were interpreted by Blagborough and Breed (1967) as relict protalus ramparts formed by debris cascading down hard snow or firn and accumulating at its downslope margins. Reinvestigation of this site suggests that this interpretation requires revision: there is no rockfall source for the debris, the implied firn gradient is insufficient for supranival debris movement, and the debris lobe microtopography, distal slope gradients and lack of consistent clast-size organization are inconsistent with the characteristics of active protalus ramparts. Alternative origins as moraines, avalanche impact landforms, rockslide runout ridges or the products of snow push or blockslope creep appear implausible. We suggest that the most likely genesis of the debris lobes, their associated ridges and other surface topography is that of rock-glacier creep, through development of massive ice under a cover of coarse debris supplied by movement of blockfield debris down the ∼24° slope at the rear of the bench. If valid, this interpretation: (1) indicates former permafrost at the time of rampart formation; and (2) implies that classification of rock glaciers requires to be widened to include blockslope-sourced examples. Copyright © 2006 John Wiley & Sons, Ltd.

The Utilization of RADARSAT-1 Imagery for the Characterization of Terrestrial Impact Landforms

RÉSUMÉCinq grandes structures complexes d'impact ont été examinées afin de déterminer l'utilité des données RADARSAT-1 pour l'analyse des formes de relief. Toutes les formes d'impacts étudiées étaient très apparentes dans les données RADARSAT-1. En particulier, il a été possible de superposer les caractéristiques des patrons de fractures de ces structures d'impact sur les patrons régionaux, permettant ainsi la production d'un patron isotropique de fracturation à l'intérieur du plancher du cratère et d'un halo périphérique de fracturation radiale. Il est évident toutefois que la profondeur et l'importance de l'érosion de même que les variations lithologiques pour chacune des structures d'impact individuelles ont beaucoup d'influence sur l'apparence générale et la visibilité de la fracturation reliée aux impacts dans les données RADARSAT-1. Les dimensions du rebord et l'étendue de la fracturation visible dans les données sont comparables aux estimés antérieurs basés sur des études de terrain. Dans certains cas, les données RADARSAT-1 peuvent servir comme outil pour la cartographie lithologique. Par exemple, les roches issues de la fusion lors de l'impact sur le site de la structure de Manicouagan ont une apparence caractéristique sur les données radar, dû à l'homogénéité de leur structure et aux effets subséquents de la glaciation. Il est aussi possible d'utiliser les données RADARSAT-1 pour la cartographie des contacts lithologiques dans l'image de la structure Haughton sur l'Ile Devon, dans l'Arctique canadien, étant donné que les zones de réflectivité différentes correspondent aux cartes géologiques de la zone. En conclusion, les données RADARSAT-1 sont utiles pour caractériser les structures d'impact étudiées compte tenu toutefois des caractéristiques étudiées ou mises en relief et en tant qu'outil pour la cartographie synoptique. Dans tous les cas, dans le contexte de la cartographie structurale/lithologique afin d'assurer un niveau de confiance suffisant dans le processus d'interprétation des données radar, l'utilisation d'autres sources d'information généralement associées aux données terrain s'est avérée nécessaire.

Snow-Avalanche Impact Landforms: A Brief Discussion of Terminology

It is suggested that features produced by the erosional impact of snow avalanches on water bodies be termed snow-avalanche impact landforms and deposits. The specific examples described by Matthews and McCarroll (1994) and Smith et al. (1994) are seen as distinctive end members of the range of depositional landforms produced by these processes.

Snow-Avalanche Impact Landforms in Breheimen, Southern Norway: Origin, Age, and Paleoclimatic Implications

Twelve snow-avalanche ramparts in Jostedalen and Sprongdalen (Breheimen, southern Norway) are investigated to elucidate processes of formation, the history of avalanche activity, and their potential for paleoclimatic reconstruction. Variation in the form of these riverbank boulder ramparts reflects local patterns of avalanche impact. Differences in clast roundness between ramparts, avalanche tracks, and river beds indicate that, on average, 50 to 60% of the clasts in the ramparts originate from river bedload as opposed to avalanche source areas or tracks. Rampart clasts increase in roundness downstream over a distance of 12 km, and the contribution from the river bed varies from 26 to 80% depending on local factors. Conventional lichenometric dating suggests ages for the initiation of rampart formation of 250 to 2000 yr, but they probably have a much longer history. Lichen-size frequency distributions, using the largest lichen from each of n boulders, reflect the age-frequency of surface boulders, providing a record of late Holocene avalanche activity. A simulation model suggests that maximum avalanche activity affected nine of the ramparts during the 19th century, after the peak of the Little Ice Age. The pattern of avalanche activity differs from the pattern of glacier variations but is in close agreement withmore » that of debris-flow activity. The ramparts may yield a valuable proxy record of winter snowfall. 48 refs., 12 figs., 4 tabs.« less

Avalanche impact landforms on Ben Nevis, Scotland

Abstract A 75 m long boulder rampart at 910 m altitude crosses a bedrock step in Coire na Ciste, Ben Nevis, and dams a small tarn (Lochan Coire na Ciste). The rampart and tarn occur at a break of slope at the foot of an extensive avalanche chute, and are interpreted as avalanche impact landforms, the first to be identified in Britain. The tarn is inferred to have formed through excavation of debris by repeated avalanche impact and the rampart by the accumulation of debris thrown up by impacting snow avalanches. Aprons of loose, angular debris that extenddownslope of the rampart and at the foot of an adjacent avalanche chute are considered to represent deposition in avalanche runout zones. Abundant recently‐deposited boulders on the rampart and debris aprons indicate recent accumulation and suggest that the geomorphic effectiveness of avalanching snow on Scottish mountains may be (at least locally) much more effective than recent accounts have suggested.

Avalanche Impact Landforms in Troms, North Norway

Snow avalanche impact landforms have been found at many localities in Troms, North Norway. Three morphological varieties occur: a) avalanche impact tongues—tongue-shaped debris accumulations on the distal banks of streams, b) avalanche impact pits—water-filled depressions having a distal tongue-shaped accumulation, c) avalanche impact pools—submerged depressions occurring in larger water bodies and bounded distally by a debris ridge. The features have formed by the cumulative effect of repeated snow avalanche impact whereby debris is ejected from the impact area and deposited distally.

Avalanche Impact Landforms in Troms, North Norway

Avalanche Impact Landforms in Troms, North Norway