Morphology Of Landforms Research Articles

Regional-scale, high-resolution measurements of hilltop curvature reveal tectonic, climatic, and lithologic controls on hillslope morphology

Climate, tectonics, lithology, and biology are encoded within the morphology of landforms. Hillslopes record uplift and erosion rate through hilltop curvature, in which sharper, more convex hilltops correspond with more rapid erosion rates. However, past hilltop curvature studies that map uplift and erosion rates have been limited to small spatial scales largely due to relatively slow speeds of curvature measurement techniques. This lack of regional-scale observations has made deconvolving the relative contributions of tectonics, climate, and lithology to hillslope morphology a challenge. Here, we used high performance computing and continuous wavelet transforms of topography to rapidly map hilltop curvature in the steep and dissected Oregon Coast Range (OCR) and the adjacent gentler Cascadia Forearc Lowland (CFL) in western Oregon, amounting to ∼43,000 km2 of 1-meter lidar data. We additionally compared mapped hilltop curvature to published erosion rates derived from cosmogenic 10Be, including 11 newly sampled watersheds. We observed that hilltops are systematically sharper in the OCR than in the CFL, and we noted a linear relationship between catchment-averaged erosion rate and hilltop curvature, consistent with previous observations and theory that erosion rate scales linearly with hilltop curvature in soil-mantled landscapes. The boundary between the OCR and CFL, as demarcated by hilltop curvature, is often abrupt and occurs across mapped structures that separate disparate baselevels but where lithology and mean annual precipitation remain constant. Thus, while we observed significant variability in hilltop curvature that results from secondary lithologic and climatic controls, our results demonstrate that hillslope morphology in western Oregon is set primarily by uplift via tectonically-controlled baselevel lowering rates. These regional interpretations additionally highlight the computational advantages of the wavelet transform for rapidly quantifying hilltop curvature.

A statistical evaluation of the morphological variability of shortening landforms on Mercury

Observations of Mercury from both the Mariner 10 and MESSENGER missions showed that Mercury has a global population of shortening landforms, with several thousands of individual structures identified to date. The accommodation of widespread tectonic shortening is widely regarded to be the result of global contraction—the long, sustained cooling of the interior that has caused the planet to shrink. Shortening landforms on Mercury have been traditionally categorized into three distinct categories: lobate scarps, wrinkle ridges, and high-relief ridges. Although the clearest examples of shortening landforms at the time were used to describe and define these categories qualitatively, later studies showed that shortening landforms on Mercury display morphological characteristics that do not make for a ready classification into one of these “traditional” groups. More recently, other studies have classified shortening landforms based on the terrain that those landforms reside in to avoid generalizing morphology. In this study, we quantitatively assess the shape of shortening landforms by measuring and compiling a suite of 12 morphological parameters for 100 such structures across the planet. These parameters were evaluated for their importance in defining categories using two multivariate statistical analyses, a Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). These methods allow us to assess any correlation that the traditional categories, terrain types, or alternative classification schemes have with the variation observed across our set of measurements. Our results show that the morphologic characteristics of shortening landforms on Mercury are not accurately captured by traditionally recognized groups. Instead, shortening landforms fall along a morphological spectrum, where only a few ideal examples of lobate scarps or wrinkle ridges provide clear endmembers. Therefore, despite the frequent use of the terms “lobate scarps” and “wrinkle ridges” in works regarding planetary tectonics, we find that such terminology does not appropriately define the morphology of shortening landforms found on Mercury and may lead to the generalization, or misinterpretation of landforms described as accommodating shortening on Mercury's surface. Future studies should test if a distinction between the landforms is found in the underlying thrust fault systems.

Assessment of Shoreline Change Along The Sandy Beach of Ellembelle District of Ghana

Sandy beaches are most popular tourists and fish landing sites, and serve as habitat for several endangered species. However, sandy beaches more vulnerable to coastal erosion, particularly those along open oceans. Assessment of shoreline change using reliable dataset aid in understanding the morphology of coastal landforms, the processes associated with their occurrence and support decision making. This paper analysed available multi-temporal spatial dataset and field observations using GNSS techniques to assess the shoreline change along the study area. The shoreline features were extracted from 1974 topographic map and 2005 orthophotographs using the High Water Line (HWL) in conjunction with 2020 spatial data. Shoreline change statistics were computed using DSAS. A geodatabase was created, transects were cast and the shoreline change rates computed using EPR, LRR and WLR methods. Both accretion and erosion were recorded with mean erosion rate of 0.97 m/year. It was observed that sections of the shoreline nourished by Ankobra and Amunzuri rivers were experiencing some accretion, particularly the mouth of the Amuzuri river. The estuary of Amunzuri river was found to be drifting eastwards at a rate of 5.4m/year possibly due to tides, waves and currents. The study concludes that in spite of the littoral drift eastwards, fluvial sediment supplied by coastal rivers accounts for the relative stability of shoreline in the area. Policy formulation regarding possible damming of coastal rivers by government under the ‘one district one dam’ agenda must be carefully considered to avert high levels of erosion along the western coast of Ghana.

Effect of the Mazar Tagh Mountains on Aeolian landforms in the western Taklamakan Desert, northwestern China

Topographic obstacles across the Earth and other planetary bodies are important factors affecting the morphology of aeolian landforms. Compared to general-scale obstacles (e.g., shrubs, nebkhas, residual hills), the effects of mountain-scale obstacles on aeolian landforms have rarely been investigated. Here, we studied the effect of the Mazar Tagh Mountains as a natural mountain-scale obstacle on aeolian landforms in the western Taklamakan Desert, northwestern China. A comprehensive analysis was conducted on the characteristics of aeolian landforms under the effect of the Mazar Tagh Mountains through aeolian sand parameters derived from the wind regime, grain-size parameter and the recent dune growth mechanisms. Our findings show that the Mazar Tagh Mountains change the spatial distribution of drift potential and grain-size parameters from the north to the south, resulting in distinctly different dune orientations and dune morphologies on both sides of the mountains. It was also found that mountains could block most sand transported from the north to the south. The Mazar Tagh Mountains block approximately 13.4 % of the resultant drift potential and 62.1 % of sand supply from north to south, respectively. However, aeolian landforms inside the sand transport channel or notch show high consistency since there is no obstacle. Combined with wind flow simulations, we suggest that mountains affect aeolian landforms by disrupting the wind flow and sand supply. Finally, we infer that the effects of mountain-scale obstacles on the dynamics of aeolian landform may be used to bring new constraints on the spatial distribution patterns of dune fields.

Morphology of Dome- and Tepee-Like Landforms Generated by Expansive Hydration of Weathering Anhydrite: A Case Study at Dingwall, Nova Scotia, Canada

The gypsum-anhydrite rocks in the abandoned quarry at Dingwall (Nova Scotia, Canada) are subjected to physical and chemical weathering, including hydration of the anhydrite, i.e., its transformation into secondary gypsum under the influence of water. This process is known to lead to the localized volume increase of the rock and the formation of spectacular hydration landforms: domes, tepees and ridges. Cavities appearing in the interior of these domes are often unique hydration caves (Quellungshöhlen in German). For the first time, this paper gives detailed geomorphometric characteristics of the 77 dome- and tepee-like hydration landforms growing today at Dingwall based on their digital surface models and orthophotomaps, made with the method of photogrammetry integrated with direct measurements. The length of hydration landforms varies from 1.86 to 23.05 m and the relative height varies from 0.33 to 2.09 m. Their approximate shape in a plan view varies from nearly circular, through oval, to elongated with a length-to-width ratio rarely exceeding 5:2. Length, width and relative height are characterized by moderate mutual correlation with proportional relations expressed by linear equations, testifying that the hydration landforms generally preserve the same or very similar shape independent of their sizes. The averaged thickness of the detached rock layer ranges from 6 to 46 cm. The size of the forms seems to depend on this thickness—the forms larger in extent (longer) generally have a thicker detached rock layer. Master (and other) joints and, to a lesser extent, layering in the bedrock influence the development of hydration landforms, particularly by controlling the place where the entrances are open to internal cavities or caves. Three structural types of the bedrock influencing the growth of hydration forms were recognized: with master joints, with layering and with both of them. The latter type of bedrock has the most complex impact on the morphology of hydration landforms because it depends on the number of master joint sets and the mutual orientation of joints and layering, which are changeable across the quarry. The durability of the hydration forms over time depends, among others, on the density of fractures in the detached rock layer.

Morphometry and morphology of fan-shaped landforms in the high-Arctic settings of central Spitsbergen, Svalbard

In this study, the distribution, morphometry and morphology of alluvial fans and colluvial cones were investigated in a high-Arctic, periglacial environment. The main aims were to present their surface morphology types, analyse the relationship between the morphometric properties of fans and their catchments, and to investigate potential factors controlling the morphometry of fans. Data from a set of 297 fan-shaped landforms in central Spitsbergen, Svalbard, were presented and analysed to ascertain factors likely to influence their distribution and character. First, based on the dominant morphological processes, the studied landforms were divided into three groups: fluvial-flow-dominated fans, debris-flow-dominated fans, and colluvial fans. Then, to analyse the relationship between fans and their catchments, 20 variables were investigated. Those analyses indicate that small catchments, characterised by a low relief and high Melton's R number, tend to produce small and steep fans. This tendency was most visible for colluvial fans and debris-flow-dominated fans but less so for fluvial-flow-dominated fans. The latter tend to adjust stronger to the local topography. However, in all cases, these associations were weaker than in morphometry studies based on data from other climatic settings. The most important controls on the distribution of the studied fan-shaped landforms seem to be the availability of accommodation space (related to deglaciation time) and local erosion base level.

Characterisation of aeolian sediment accumulation and preservation across complex topography

Topography fundamentally influences the distribution and morphology of aeolian landforms via the modification of surface wind flow and the creation of space for sediment deposition. This has been observed at both landform (individual topographic dune forms) and macro-landscape (sand sea) scales. Although previous studies have considered several aspects of the impact of topography on aeolian landforms, the patterns of landscape-scale aeolian sediment accumulation that emerge at the meso-scale, within topographically complex environments have received less consideration.To address this, we present an approach that combines information on the presence of surficial sand (via remote sensing) with the morphometric feature classification method, LandSerf. Using the Cady Mountains in the Mojave Desert as a case study, we explore the relationships between sand cover and topographic indices over length scales of 102–103 m. Field observations are then used to refine our understanding of these patterns.Aeolian deposits across the Cady Mountains are strongly controlled by the topography. Although sand cover is often continuous and highly variable in depth, four archetypal “accommodation space types” are identified from the morphometric analysis: Slopes, Plains, Valley-Fills, and Slope-Valley composite. Specific aeolian landforms within these accommodation spaces may manifest as sand ramps and climbing - falling dunes, particularly on mountain front Slopes, and as sand sheets on downwind Plains within the mountain block. In areas of high sediment supply these may also coalescence, as exemplified by the extensive and compositionally complex Slope-Valley composites in the northern Cady Mountains.In conjunction with field observations, we argue that topography, moderated by proximity to sediment supply, strongly influences the character of the aeolian sedimentary record. However, even within the relatively complex landscape studied here, 90% of the mapped sand accumulation is associated with the four identified accommodation space types. The implication is that areas of such complex topography are amenable to analysis within the scheme outlined and that this can potentially be used to support interpretations of accompanying dune chronologies.

Методика изучения морфологии абразионно-аккумулятивных берегов Западного побережья Крыма с применением БЛА и ГНСС (на примере участка территории Большого Севастополя)

The method of studying the abrasion-accumulative coast of the Western coast of Crimea within the urban area of Sevastopol includes remote sensing using unmanned aerial vehicles (UAVs) and field studies of the morphology and structure of abrasion and landslide landforms of the coast. As a result of the research, the morphological zoning of the abrasion-accumulative coast was established. The formation of the morphological zoning of the abrasion-accumulative coast (according to I.S. Shchukin) during the last 150 years took place at a constant level of the Black Sea. Analysis of the coast from previously published multi-temporal maps and aerospace photographs revealed different stages in the movement of the coastline and landslide scarp. Since 1966, the coastal area has been used for low-rise residential development, which may have influenced the activity of landslide processes in the coastal strip. Remote sensing using UAVs consists of aerial photography of the research area along the planned flight route at altitudes of 20–100 m, with further compilation of a large-scale orthophotomap from a mosaic of images with geospatial fixation of images to the signs of the reference long-term local geodetic network, previously measured by the methods of global navigation satellite systems (GNSS ), as well as the formation of a digital elevation model (DEM) and the compilation of derived maps and plans on its basis in the environment of geographic information systems (GIS), for the analysis of the morphometry of the relief and modeling. The developed method of remote sensing of the Earth with the use of UAVs and simultaneous field studies makes it possible to organize operational monitoring of dynamically developing abrasion-accumulative shores.

Aeolian Processes in Forest-Steppe Landscapes in the Upper Angara Region in the Holocene

Presented are the results from investigating the aeolian sand massifs in the Belaya river valley. The Belaya, Kholmushino and Usolye massifs with the area of 2, 1.4 and 269 km, respectively, are singled out. They are differentiated by the degree and magnitude of manifestation of aeolian processes, and by the morphology of landforms. The Belaya massif is characterized by narrow gully‒low ridge topography. The initial fluvial relief is moderately modified because of the isolated location of the area in the spur of the incised meander and its boundedness by the slope of the narrow segment of the valley. In the Kholmushino massif located in the zone of contact of the segment of the incised channel and the broadening of the valley, aeolian forms were able to evolve fully but they occur only along narrow terraced surfaces of the rectilinear segment of the valley. The more favorable conditions emerged for the evolution of the Usolye massif. The broad-floodplain type of Belaya channel promoted accumulation of significant volumes of sandy material and its free transport in the process of aeolian morphogenesis. The most intense aeolian accumulation was observed in the lower reaches of the Belaya at the interface of the Late Glacial and Holocene (from 13.1 kyr BP) and was proceeding throughout the Early Holocene until 8.9 kyr BP when there occurred a decrease in activity of the aeolian processes and an intense soil formation began. The landscape-climatic conditions of the Atlantic period were favorable for the attenuation of aeolian activity and for a gradual fixation of sands by vegetation. The intensification phases of the aeolian processes were replaced by stages of a decrease in activity of the aeolian morphogenesis and soil formation in the intervals 9.3‒8.6; 6.7‒6; 3.5‒2.6 and 1.2‒0.9 kyr BP. The pedogenesis stages coincided with an increase in heat and moisture availability. Analysis of the findings suggests the rhythmic behavior in the evolution of the region’s natural environment in the Late Glacial with the manifestation of aeolian phases every 4‒5 ka and phases of intense soil formation every 1.9‒2.5 ka.

Pliocene–Pleistocene glacimarine shelf to slope processes in the south‐western Barents Sea

AbstractThe glacimarine shelf‐edge is a complex depositional environment in which the interplay between accommodation and glaciation has played an important role in influencing sediment deposition and margin architecture. It can be challenging to unravel the history of basin infill in these areas, particularly where landforms are deeply buried. This study presents an integrated workflow for deciphering the architecture and evolution of erosional and depositional elements in a crucial location of the south‐western Barents Sea margin, with a focus on the comparatively poorly understood processes and patterns of glacimarine sedimentation that occurred during the Pliocene and Early Pleistocene. Wellbore interpretations of lithology are combined with the analysis of seismic facies, geomorphology and attributes using merged 3D seismic reflection data to investigate the morphology and development of buried landforms and depositional features on the outer‐shelf, shelf edge and upper‐slope. The Pliocene (preglacial) slope system is dominated by upper‐slope channels, upper‐slope channels with associated sediment lobes, and mass‐transport deposits. The first appearance of mega‐scale glacial lineations in the study area is close to the onset of the Pleistocene (around 2.58 Ma), suggesting that an ice stream reached the palaeo‐shelf edge during the earliest Pleistocene. The prevalence of upper‐slope channels and mass‐transport deposits throughout the Pleistocene stratigraphy shows that the basinwards transfer of sediment took place mainly by evacuation of sediment through relatively linear channels combined with mass‐movement events. The results presented in this study have implications for understanding the glacial history of the south‐western Barents Sea and sedimentary processes on glacimarine shelf edges more generally.

Evolution of high-Arctic glacial landforms during deglaciation

Glacial landsystems in the high-Arctic have been reported to undergo geomorphological transformation during deglaciation. This research evaluates moraine evolution over a decadal timescale at Midtre Lovénbreen, Svalbard. This work is of interest because glacial landforms developed in Svalbard have been used as an analogue for landforms developed during Pleistocene mid-latitude glaciation. Ground penetrating radar was used to investigate the subsurface characteristics of moraines. To determine surface change, a LiDAR topographic data set (obtained 2003) and a UAV-derived (obtained 2014) digital surface model processed using structure-from-motion (SfM) are also compared. Evaluation of these data sets together enables subsurface character and landform response to climatic amelioration to be linked. Ground penetrating radar evidence shows that the moraine substrate at Midtre Lovénbreen includes ice-rich (radar velocities of 0.17 m ns−1) and debris-rich (radar velocities of 0.1–0.13 m ns−1) zones. The ice-rich zones are demonstrated to exhibit relatively high rates of surface change (mean thresholded rate of −4.39 m over the 11-year observation period). However, the debris-rich zones show a relatively low rate of surface change (mean thresholded rate of −0.98 m over the 11-year observation period), and the morphology of the debris-rich landforms appear stable over the observation period. A complex response of proglacial landforms to climatic warming is shown to occur within and between glacier forelands as indicated by spatially variable surface lowering rates. Landform response is controlled by the ice-debris balance of the moraine substrate, along with the topographic context (such as the influence of meltwater). Site-specific characteristics such as surface debris thickness and glaciofluvial drainage are, therefore, argued to be a highly important control on surface evolution in ice-cored terrain, resulting in a diverse response of high-Arctic glacial landsystems to climatic amelioration. These results highlight that care is needed when assessing the long-term preservation potential of contemporary landforms at high-Arctic glaciers. A better understanding of ice-cored terrain facilitates the development of appropriate age and climatic interpretations that can be obtained from palaeo ice-marginal landsystems.

Postglacial relative sea level change at Fildes Peninsula, King George Island (West Antarctic)

Analysis and integration of data obtained in our field and laboratory investigations of 2008–2012 together with results of previous paleogeographic studies were conducted to reveal parameters and factors of the post-glacial changes in the relative sea-level on the Fildes Peninsula and the King George Island. Results of dating of organic material taken from cross-sections of Quaternary deposits, data on morphology of marine landforms as well as on bottom sediments in lakes were used to construct a curve of changes in the relative sea-level. Our research has shown that the rapid rise of relative sea level in the area (since the beginning of the Holocene) decelerated about 8000 years BP, achieving its maximum about 7000 years BP. This was followed by the fall of relative sea-level (the land elevation) by 18–20 m in total, and it was characterized by relatively high rate of fall during periods of 6000– 5000 years BP, 4000–2500 years BP, and during the last 1500 years; the rate decreased in 5000–4000 years BP and 2500– 1600 years BP. The changes in relative sea level in this region were determined by the following factors: the eustatic component of the global changes in sea-level and, possibly, oscillations in the global sea level of another nature; local parameters of the Last glacial maximum; a course of the Peninsula deglaciation; regional physical characteristics of the Earth's crust and the mantle substances; local tectonic processes, including the isostatic rebound. Since the beginning of the Holocene up to about 7000 years BP, the main contribution to changes of the relative sea-level in this area was made by the global eustatic factor. The subsequent fall of the relative sea-level (elevation of the Peninsula surface) proceeded under condition of reduced role of the eustatic factor and predominance of other factors.

Modern morpho-sedimentological patterns in a tide-dominated estuary system: the Bay of Brest (west Britanny, France)

ABSTRACTLong-studied with respect to its sedimentological features (1897), the Bay of Brest (Western Britanny, France) is a textbook example of a tide-dominated estuary. Characterised by macrotidal conditions, this estuary system is sheltered from the open sea (Iroise Sea) by a narrow strait that partitions the wave tide influences and continental/marine inputs. Sediments are supplied to the bay both by rivers (the Aulne and Elorn rivers) and by marine tidal currents. This study presents new analyses of detailed facies and morphological patterns, based on the integration of multisource data compiling seabed sampling, swath and LIDAR bathymetry, and backscatter imagery. The Main Map, at a scale of 1:90,000, contains (1) a sedimentological distribution using the ‘Code Manche’ classification, (2) a morphological map, and (3) bathymetric mapping which presents the morphology of marine and terrestrial landforms. This work may lay the foundation for a future study on sedimentary transport in a unique and confined coastal environment.

Paleotopographic controls on loess deposition in the Loess Plateau of China

AbstractThe underlying pre‐existing paleotopography directly influences the loess deposition process and shapes the morphology of current loess landforms. An understanding of the controlling effects of the underlying paleotopography on loess deposition is critical to revealing the mechanism of loess‐landform formation. However, these controlling effects exhibit spatial variation as well as uncertainty, depending on a study's data sources, methodologies and particular research scope. In this study, the geological history of a study area in the Loess Plateau of China that is subject to severe soil erosion is investigated using detailed geological information and digital elevation models (DEMs), and an underlying paleotopographic model of the area is constructed. Based on the models of modern terrain and paleotopography, we introduce a watershed hierarchy method to investigate the spatial variation of the loess‐landform inheritance relationship and reveal the loess deposition process over different scales of drainage. The landform inheritance relationships were characterized using a terrain‐relief change index (TRCI) and a bedrock terrain controllability index (BTCI). The results show that the TRCI appears to have an inverse relationship with increasing research scope, indicating that, compared with the paleotopography of the region, modern terrain has lower topographic relief over the entire area, while it has higher topographic relief in the smaller, local areas. The BTCI strengthens with increasing drainage area, which demonstrates a strong controlling effect over the entire study area, but a weak effect in the smaller, local areas because of the effect of paleotopography on modern terrain. The results provide for an understanding of the spatial variation of loess deposition in relation to paleotopography and contribute to the development of a process‐based loess‐landform evolution model. Copyright © 2015 John Wiley & Sons, Ltd.

Fluvial landforms and their implication towards understanding the past climate and seismicity in the northern Katrol Hill Range, western India

The tectonically active Kachchh peninsula in western India lies in the southwest monsoon trajectory and hence provides a rare opportunity to decipher the temporal changes in climate–tectonics interaction in the evolution of the fluvial landforms. Reconstructions based on geomorphology, sedimentology, and geochemistry supported by optical chronology suggest that the fluvial aggradation in the region was initiated during the onset of the Indian Summer Monsoon (ISM) after the Last Glacial Maximum (LGM). The sedimentary characteristics and major elemental concentrations suggest that the sediments are dominated by fluvially reworked miliolites with subordinate contribution from the Mesozoic sandstones and shales and were deposited with the initiation of the ISM after the LGM. Temporal changes in facies architecture and major element concentrations suggest a progressive strengthening of the monsoon between 17 and 12 ka. This was succeeded by an overall strengthened ISM phase with fluctuations after 12 ka and <8 ka. Following this, a gradual decline in the ISM is inferred until around 3 ka. However, presence of the younger valley-fill sediments which are dated to ∼1 ka are ascribed to a short-lived phase of renewed strengthened ISM in the region before the onset of present day aridity.Based on the morphology of the fluvial landforms, two major events of enhanced uplift can be suggested. The geomorphic expression of the older uplift event dated to >17 ka is represented by the beveled Mesozoic bedrock surfaces which accommodated the post LGM valley-fill aggradation. The younger event of enhanced uplift which is assigned to <3 ka was responsible for the incision of the fill sediments and the Mesozoic bedrock, and the evolution of the present day fluvial landforms. The time averaged incision/uplift rate indicates that the Katrol Hill Range is uplifting at the rate of ∼4 mm per year, implying seismically active terrain.

Visualizations of coastal terrain time series

In coastal regions, water, wind, gravitation, vegetation, and human activity continuously alter landscape surfaces. Visualizations are important for understanding coastal landscape evolution and its driving processes. Visualizing change in highly dynamic coastal terrain poses a formidable challenge; the combination of natural and anthropogenic forces leads to cycles of retreat and recovery and complex morphology of landforms. In recent years, repeated high-resolution laser terrain scans have generated a time series of point cloud data that represent landscapes at snapshots in time, including the impacts of major storms. In this article, we build on existing approaches for visualizing spatial–temporal data to create a collection of perceptual visualizations to support coastal terrain evolution analysis. We extract terrain features and track their migration; we derive temporal summary maps and heat graphs that quantify the pattern of elevation change and sediment redistribution and use the space–time cube concept to create visualizations of terrain evolution. The space–time cube approach allows us to represent shoreline evolution as an isosurface extracted from a voxel model created by stacking time series of digital elevation models. We illustrate our approach on a series of Light Detection and Ranging surveys of sandy North Carolina barrier islands. Our results reveal terrain changes of shoreline and dune ridge migration, dune breaches and overwash, the formation of new dune ridges, and the construction and destruction of homes, changes which are due to erosion and accretion, hurricanes, and human activities. These events are all visualized within their geographic and temporal contexts.

Testing 3D landform quantification methods with synthetic drumlins in a real digital elevation model

Metrics such as height and volume quantifying the 3D morphology of landforms are important observations that reflect and constrain Earth surface processes. Errors in such measurements are, however, poorly understood. A novel approach, using statistically valid ‘synthetic’ landscapes to quantify the errors is presented. The utility of the approach is illustrated using a case study of 184 drumlins observed in Scotland as quantified from a Digital Elevation Model (DEM) by the ‘cookie cutter’ extraction method. To create the synthetic DEMs, observed drumlins were removed from the measured DEM and replaced by elongate 3D Gaussian ones of equivalent dimensions positioned randomly with respect to the ‘noise’ (e.g. trees) and regional trends (e.g. hills) that cause the errors. Then, errors in the cookie cutter extraction method were investigated by using it to quantify these ‘synthetic’ drumlins, whose location and size is known. Thus, the approach determines which key metrics are recovered accurately. For example, mean height of 6.8m is recovered poorly at 12.5±0.6 (2σ) m, but mean volume is recovered correctly. Additionally, quantification methods can be compared: A variant on the cookie cutter using an un-tensioned spline induced about twice (×1.79) as much error. Finally, a previously reportedly statistically significant (p=0.007) difference in mean volume between sub-populations of different ages, which may reflect formational processes, is demonstrated to be only 30–50% likely to exist in reality. Critically, the synthetic DEMs are demonstrated to realistically model parameter recovery, primarily because they are still almost entirely the original landscape. Results are insensitive to the exact method used to create the synthetic DEMs, and the approach could be readily adapted to assess a variety of landforms (e.g. craters, dunes and volcanoes).

The Morphology and Spatial Distribution of Late Quaternary Periglacial Landforms, Snake Range, Nevada: A Gis-Based Approach to Prioritizing Field Sites

We present new data describing relict periglacial landforms preserved in the interior Great Basin of the southwestern United States. This summary is significant because a thorough understanding of the occurrence and spatial distribution of these landforms is still lacking after 60 years of geomorphic studies in this region. This is largely because many landforms are often un-recognized and because many mountains in the Great Basin are remote and offer poor access. To help address this knowledge gap, we use a GIS with high-resolution imagery and field mapping to identify and describe features that indicate a locally extensive periglacial environment existed in the Snake Range of east-central Nevada during the Late Quaternary. We also compare the location of these landforms with solar radiation models produced using ESRI's Solar Analyst to evaluate the efficacy of using solar modeling as means to predict suitable field sites for periglacial landforms. This simple modeling technique accurately identifies the location of known periglacial landforms in the Snake Range and therefore we believe it could be used to prioritize sites of interest throughout the Great Basin.

Morphostratigraphy and palaeoclimate appraisal of the Leh valley, Ladakh Himalayas, India

In the present paper we study morphology, occurrence and mutual interrelationship of erosional (amphitheaters) and depositional landforms belonging to glacial (moraines), fluvio-glacial (glacial out wash), mass wasting (alluvial fans), aeolian (obstacle dune and sand sheets) and lacustrine (palaeo-lake sediments) processes within the Leh valley. These landforms are the geomorphic expression of past deglaciation grouped into five Formative Stages of Landform (FSL 1 to FSL 5) development in the Leh valley. The broad age bracket for the formative stages are based on the empirical relationship of the landforms, available chronology and their correlation with comparable climate phases. The retreat of glaciers in the Leh valley, along the southern slopes of Ladakh hill range and their retention over the northern slopes and Karakoram is further explained.

Late Quaternary ice flow and sediment delivery through Hinlopen Trough, Northern Svalbard margin: Submarine landforms and depositional fan

The morphology and distribution of submarine landforms in Hinlopen Trough, Northern Svalbard margin, and the upper continental slope beyond, are investigated using swath-bathymetric data, together with side-scan sonar, acoustic profiler records and sediment cores. Sun-illuminated images reveal a number of landform assemblages on the sea floor of Hinlopen Trough and confirm that this depression was occupied by an ice stream during the Late Weichselian glaciation around 20 ka before present. The geomorphology of the inner-shelf is characterised by bedrock drumlins and ice-sculpted bedrock. There is a middle-shelf transition from a rock bed to an unconsolidated sedimentary bed that contains highly-attenuated drumlins and megaflutes formed within a dark grey, matrix-supported diamict, interpreted as subglacial till. Outer-shelf landforms are mainly iceberg ploughmarks. The geomorphological imprint identified from Hinlopen Trough is similar to that of many former ice streams; the trough is dominated by elongate landforms orientated parallel to the inferred flow direction and is lacking in transverse features indicative of inter-ice stream locations. A characteristic down-flow progression in landform elongation is also observed, suggesting an increase in ice velocity across the continental shelf. The lack of grounding-zone features imaged from swath-bathymetric data implies that deglaciation was probably rapid within the trough. A large depositional fan exists on the upper continental slope beyond the trough, characterised by debris flow deposits relating to the down-slope transport of glacigenic sediment. Order of magnitude calculations of the volume of glacigenic sediment on the continental slope indicate that the ice stream provided high rates of debris delivery of around 5–7.5 m/ka. This suggests that Hinlopen Trough ice stream represented a major route for the transfer of ice and debris to the Hinlopen Fan on the northern continental margin of Svalbard during the Late Weichselian glaciation.