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Abstract: Drumlins are subglacial bedforms streamlined in the direction of ice flow. Common in deglaciated landscapes, they have been widely studied providing rich information on their internal geology, size, shape, and spacing. In contrast with bedform investigations elsewhere in geomorphology (aeolian and fluvial dunes and ripples for example) most drumlin studies derive observations from relict, and thus static features. This has made it difficult to gain information and insights about their evolution over time, which likely hampers our understanding of the process(es) of drumlin formation. Here we take a morphological approach, studying drumlin size and spacing metrics. Unlike previous studies which have focussed on databases derived from entire ice sheet beds, we adopt a space‐for‐time substitution approach using individual drumlin flow‐sets distributed in space as proxies for different development times/periods. Framed and assisted by insights from aeolian and fluvial geomorphology, we use our metric data to explore possible scenarios of drumlin growth, evolution and interaction. We study the metrics of the size and spacing of 36 222 drumlins, distributed amongst 71 flow‐sets, left behind by the former British‐Irish Ice Sheet, and ask whether behaviour common to other bedform phenomena can be derived through statistical analysis. Through characterizing and analysing the shape of the probability distribution functions of size and spacing metrics for each flow‐set we argue that drumlins grow, and potentially migrate, as they evolve leading to pattern coarsening. Furthermore, our findings add support to the notion that no upper limit to drumlin size exists, and to the idea that perpetual coarsening could occur if given sufficient time. We propose that the framework of process and patterning commonly applied to non‐glacial bedforms is potentially powerful for understanding drumlin formation and for deciphering glacial landscapes. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Regional scale studies of glacial cirque metrics provide key insights on the (palaeo) environment related to the formation of these erosional landforms. The growing availability of high resolution terrain models means that more glacial cirques can be identified and mapped in the future. However, the extraction of their metrics still largely relies on time consuming manual techniques or the combination of, more or less obsolete, GIS tools. In this paper, a newly coded toolbox is provided for the automated, and comparatively quick, extraction of 16 key glacial cirque metrics; including length, width, circularity, planar and 3D area, elevation, slope, aspect, plan closure and hypsometry. The set of tools, named ACME (Automated Cirque Metric Extraction), is coded in Python, runs in one of the most commonly used GIS packages (ArcGIS) and has a user friendly interface. A polygon layer of mapped cirques is required for all metrics, while a Digital Terrain Model and a point layer of cirque threshold midpoints are needed to run some of the tools. Results from ACME are comparable to those from other techniques and can be obtained rapidly, allowing large cirque datasets to be analysed and potentially important regional trends highlighted. [ABSTRACT FROM AUTHOR]

Ground-penetrating radar (GPR) is becoming a commonly applied technique in geomorphology. However, its use in the study of subglacial bedforms has yet to be fully explored and exploited. This paper presents the results of a GPR feasibility study conducted on a drumlinized terrain in Cumbria, UK, where five drumlins were investigated using multiple radar antenna frequencies. The site was selected for the presence of nearby bedrock outcrops, suggesting a shallow drumlinized diamict-bedrock contact and a permeable lithology. Despite the clayey sediment and unfavourable weather conditions, a considerable penetration depth of ~12 m was achieved when using a 50 MHz antenna, with a separation of 1 m, trace spacing of 1 m and 128-fold vertical stack. Results indicate that the drumlinized diamict is in direct erosional contact with the bedrock. While the internal drumlin geometry is generally chaotic on the stoss side, evidence of layering dipping downflow at an angle greater than the drumlin surface profile was found on the lee side. The inter-drumlin areas comprise ~4 m of infill sediment that masks part of the original drumlin profile. Overall, this study indicates that GPR can be deployed successfully in the study of glacial bedform sedimentary architecture. [ABSTRACT FROM AUTHOR]

Abstract: The asymmetry of the planar shape of drumlins is an established paradigm in the literature and characterizes drumlins as resembling tear drops with a blunt (bullet-shaped) stoss end and a tapering (pointed) lee end. It is widely cited and never been seriously questioned. In this paper, the planar shape of 44,500 drumlins mapped in various regional settings from drumlin fields in North America and Northern Europe were objectively analysed by means of Geographic Information System tools. Two parameters were considered. The first (denoted here as As pl) focuses on the relative position of the point of intersection between the axes of the maximum length and the maximum width. It is defined as the distance between the upstream (i.e. beginning of the drumlin) and the intersection point (measured along the longitudinal axis) divided by the entire length of the long axis. Results indicate that the intersection point of the majority of drumlins (64%) is very close to the longitudinal midpoint (0.33< As pl <0.66). The second parameter (As pl_A ) is defined as the ratio between the area of the upstream half of the drumlin to that of the entire drumlin. Results show that for most drumlins (81%), the upper half area is almost as large as the down-half (0.45< As pl_A <0.55). Taken together, these results concordantly indicate that drumlin planar shape has a strong tendency to be longitudinally symmetric and that the long-established paradigm of their plan form is false. [ABSTRACT FROM AUTHOR]

Glaciogenic sediments are present in many hydrocarbon-producing basins across the globe but their complex nature makes it difficult to characterise the reservoir-quality sedimentary units. Despite this, Ordovician glacial deposits in North Africa, and Carboniferous-Permian glaciogenic sequences in the Middle East, have been proven to host significant, economical, hydrocarbon accumulations. Additionally, discoveries have been made in the shallow (<1000 m below seabed), glacial, Pleistocene sedimentary succession of the North Sea (e.g. Peon and Aviat). This paper provides a predictive exploration framework in the form of a conceptual model of glaciogenic sediment-landform distributions. The model is based on the extensive onshore glacial sedimentary record integrated with available offshore data. It synthesises the published knowledge, drawing heavily on glacial landsystem models, glacial geomorphology and sedimentology of glaciogenic deposits to provide a novel conceptual model allowing for the efficient description and interpretation of glacial sediments and landforms in the subsurface. Subsequently, land-terminating and water-terminating ice sheet depositional systems are described and discussed, with respect to ice advance and retreat cycles. This detailed description focuses on the macro-scale stratigraphic organisation of glacial sediments with relation to the ice margin, aiding the prediction of glaciogenic sediment distributions, and their likely geometry, architecture and connectivity as reservoirs. • A novel conceptual model for the distribution of glaciogenic reservoirs. • First-pass interpretation tool for complex glaciogenic sequences. • Ice margin position controlling reservoir quality. • Identification of landforms and sediments crucial to reservoir predictability. [ABSTRACT FROM AUTHOR]

This study is focused on the geomorphology of surface sedimentary environments contained in the fluvial, tidal and wave-dominated areas of the Niger Delta. GIS techniques applied to high-quality Landsat and SPOT images were used to identify and map landforms and processes, as well as quantitatively characterise their metrics and spatial distribution. A detailed analysis shows that the extent of the Niger Delta is 70,000 km2, contrary to previous publications that reported 75,000 km2. The delta has also been remapped and classified into mega sedimentary environments: the upper deltaic plain is 69% of the total extent, while the lower deltaic plain and delta front are 25% and 6% respectively. Other subunits were distinguished and mapped within the upper deltaic plain such as fluvial channels, point bars, braid bars, oxbow lakes, and other lakes. Tidal channels, beaches and spits were identified in the lower deltaic plain and delta front. The geometries of these sedimentary bodies (landforms) appear to be relatively scale-invariant, thus meaning that from the measurement of some dimensional parameters (e.g. the length) it is possible to estimate all others (e.g. the width and overall extent). This is an aspect of great relevance in subsurface analyses where it is often difficult to predict the extent of sedimentary bodies. The correlation between channel width and length (r2 = 0.9), is the strongest relationship found between sedimentary body metrics. • This work presents the geomorphology of Niger Delta surface sedimentary environments. • GIS is applied to map landforms and quantify their metrics and spatial distribution. • Niger Delta is classified as tide-dominated, wave-influenced and fluvial-effect-Tw f. • Present-day Niger Delta geomorphology is relevant to subsurface reservoir studies. [ABSTRACT FROM AUTHOR]

Some surge-type glaciers on the High-Arctic archipelago of Svalbard have large glacitectonic composite ridge systems at their terrestrial margins. These have formed by rapid glacier advance into proglacial sediments during the active surge phase, creating multicrested moraine complexes. Such complexes can be formed during single surge advances or multiple surges to successively less-extensive positions. The few existing studies of composite ridge systems have largely relied on detailed information on internal structure and sedimentology to reconstruct their formation and links to surge processes. However, natural exposures of internal structure are commonly unavailable, and the creation of artificial exposures is often problematic in fragile Arctic environments. To compensate for these issues, we investigate the potential for reconstructing composite ridge system formation based on geomorphological evidence alone, focusing on clear morphostratigraphic relationships between ridges within the moraine complex and relict meltwater channels/outwash fans. Based on mapping at the margins of Finsterwalderbreen (in Van Keulenfjorden) and Grønfjordbreen (in Grønfjorden), we show that relict meltwater channels that breach outer parts of the composite ridge systems are in most cases truncated upstream within the ridge complex by an inner pushed ridge or ridges at their ice-proximal extents. Our interpretation of this relationship is that the entire composite ridge system is unlikely to have formed during the same glacier advance but is instead the product of multiple advances to successively less-extensive positions, whereby younger ridges are emplaced on the ice-proximal side of older ridges. This indicates that the Finsterwalderbreen composite ridge system has been formed by multiple separate advances, consistent with the cyclicity of surges. Being able to identify the frequency and magnitude of former surges is important as it provides insight into the past behaviour of surge-type glaciers and, if absolute dating is possible, allows for the assessment of surge-type glacier response to climate change on decadal to centennial timescales. Although further investigations into the internal structure of these deposits should be sought where possible, our study demonstrates that geomorphology could be an invaluable tool for reconstructing the formation of composite ridge systems. [ABSTRACT FROM AUTHOR]

Trough Mouth Fans (TMF) are sedimentary depocenters located at glaciated continental margins and consist predominantly of glacigenic debris flow deposits. The Foula wedge is a Pleistocene TMF accumulated offshore West of Shetland over the Northeast Atlantic margin. This study presents an analysis of a 3D seismic reflection dataset imaging the distal Foula wedge basin fan deposits between 1010 and 1100 m water depth, directly downslope from a gully system which was active untill the end of the last deglaciation. Results reveal, in unprecedented detail, the basal surface of this fan system and its internal complex architecture. Features typical of both debris flow deposits and turbidites are identified, including a basin channel network with linear and diverging erosional features forming distinctive terminal lobes, stacked and backstepping. The study links the seafloor morphology of the basin fan with its subsurface geomorphology, showing connection with the downslope gully system to the east. It presents evidence for a complex distal depositional system on glaciated margins, characterised by heterogeneous sediment delivery processes and deposits. A conceptual evolution model is proposed, with a glacigenic debris flow-dominated TMF at the LGM, subsequently influenced by meltwater discharges, with deposition occurring as a function of the shelf margin and slope paleo-morphology, slope substrate composition, interaction of downslope and along slope processes and ice-margin dynamics. • 3D architecture of a glacigenic basin fan system revealed in unprecedented detail. • Subsurface seismic geomorphology highlights a more heterogenous basin depositional system than previously interpreted. • Articulated basin channel network characterised by features typical of both debris flow deposits and turbidites. • Sediment delivery processes controlled by paleo-topography, substrate and meltwater in response to the ice-margin dynamics. [ABSTRACT FROM AUTHOR]

Mapping of glacial landforms has long been a cornerstone of glacial geomorphology, but it was not until the advent of remote sensing and GIS that widespread detailed mapping could be achieved. Using the examples of subglacial bedforms and the BRITICE project, I highlight how large databases of glacial geomorphological mapping can be used to: i) understand landform genesis; ii) reconstruct palaeo-ice sheets; and iii) validate ice sheet models. Arguably, glacial geomorphology has never been more useful. However, there is still room for improvement. Automated mapping techniques remain in their infancy. Yet, detailed remote sensing data at continental scales is becoming available, the scale of which is a daunting challenge for lone-manual mapping. Could machine learning hold an answer? Furthermore, completed work is often disparately stored and non-standardised. This leads to duplication of research and limits the utility of the collected datasets for future researchers. Here, I call upon the glacial geomorphological community to launch an open-access database of glacial geomorphological mapping on a global scale. [ABSTRACT FROM AUTHOR]