Terminal Moraine Ridges Research Articles

Glacier dynamics during a phase of Late Quaternary warming in Patagonia reconstructed from sediment-landform associations

The geomorphological record in glaciated landscapes can provide important information for the study of the response of glaciers to rapid climate change. This study presents a new reconstruction of the glacial history of the northern Monte San Lorenzo ice cap, southern South America, during a period of accelerated warming and deglaciation following the Antarctic Cold Reversal (14.5–12.8 ka). We present a detailed geomorphological map of the valleys to the north of Monte San Lorenzo. Sediment-landform assemblages identified include lateral and terminal moraine ridges, flutes, deltas, ice-contact fans, palaeoshorelines, kame terraces and outwash plains. We map 14 primary ice-limits, 7 of which are newly identified, and 7 of which are from previous studies, mapped here in greater detail. We devise landsystem models to formalise and document spatial and temporal changes in glacial processes and environments. Our new geomorphological mapping and landsystem reconstructions provide an important insight into the response of temperate Patagonian glaciers to rapidly-warming climate.

Glacial and submarine processes on the shelf margin of the Disko Bay Trough Mouth Fan

Fast-flowing ice streams and outlet glaciers exert a major control on glacial discharge from contemporary and past ice sheets. Improving our understanding of the extent and dynamic behaviour of palaeo-ice streams is crucial for predictions of how the cryosphere will respond to climate warming and the associated implications for global sea level. This paper presents results from two 3D-seismic surveys located on the continental shelf adjoining the Disko Bay Trough Mouth Fan (TMF), one of the largest glacial outlet systems in Greenland. Located at the seaward terminus of the c. 370km long cross-shelf Disko Trough, the Disko Bay TMF was generated by highly efficient subglacial sediment delivery onto the continental slope during repeated ice stream advances. A variety of submarine glacial landform assemblages are recognised on the seabed reflecting past ice stream activity. The 3D-seismic study covers the shallow banks located north and south of the Disko Trough and sheds focus on the seabed and the uppermost stratigraphic interval associated with the late Pleistocene development. The buried section (probably of Saalian age) contains a prominent grounding-zone wedge (GZW) in the northern and low-angle progradational packages in the southern area, indicating a period of major glacial advances to the shelf margin. Subsequently, the outer margin was influenced by glacimarine sedimentation, localized shelf-edge ice advances and sediment transport by contour currents that possibly began in the last interglacial period (Eemian). During the last (de)glaciation, the northern bank appears to have been covered by passive ice leaving a field of dead-ice deposits. In contrast, multiple sets of terminal moraine ridges observed on the southern bank suggest a slow retreat of active, grounded ice from the Last Glacial Maximum (LGM) position on the outer shelf. Isostatic and tectonic influences on relative sea level may have played a role in generating the divergent glacial configurations of the northern and southern bank areas.

Holocene glacial evolution of Mohnbukta in eastern Spitsbergen

Submarine geomorphology is one of the main tools for understanding past fluctuations of tidewater glaciers. In this study we investigate the glacial history of Mohnbukta, on the east coast of Spitsbergen, Svalbard, by combining multibeam‐bathymetric data, marine sediment cores and remote sensing data. Presently, three tidewater glaciers, Heuglinbreen, Königsbergbreen and Hayesbreen calve into Mohnbukta. Hayesbreen surged at the end of the Little Ice Age, between 1901 and 1910. The submarine landform assemblage in Mohnbukta contains two large transverse ridges, interpreted as terminal moraines, with debrisflow lobes on their distal slopes and sets of well‐preserved geometric networks of ridges, interpreted as crevasse‐squeeze ridges inshore of the moraines. The arrangement of crevasse‐squeeze ridges suggests that both landform sets were produced during surge‐type advances. The terminus position of the 1901–1910 Hayesbreen surge correlates with the inner (R.2) terminal moraine ridge suggesting that the R.1 ridge formed prior to 1901. Marine sediment cores display 14C ages between 5700–7700 cal. a BP derived from benthic foraminifera, from a clast‐rich mud unit. This unit represents pre‐surge unconsolidated Holocene sediments pushed in front of the glacier terminus and mixed up during the 1901 surge. An absence of retreat moraines in the deeper part of the inner basin and the observation of tabular icebergs calving off the glacier front during retreat suggest that the front of Hayesbreen was close to flotation, at least in the deeper parts of the basin. As the MOH15‐01 core does not penetrate into a subglacial till and the foraminifera in the samples were well preserved, the R.1 ridge is suggested to have formed prior to the deposition of the foraminifera. Based on these data we propose that a surge‐type advance occurred in Mohnbukta in the early Holocene, prior to 7700 cal. a BP, which in turn indicates that glaciers can switch to and from surge mode.

The geomorphic imprint of glacier surges into open-marine waters: Examples from eastern Svalbard

Seafloor morphology beyond nine tidewater glaciers terminating in open-marine settings in eastern Svalbard has been investigated using multibeam swath-bathymetry. Historical information on tidewater glacier fluctuations over the past century or so shows that the seafloor offshore has been exposed only recently. Most glaciers have been observed to surge or have looped surface moraines indicating past surges. During these ice advances and subsequent retreat, a well-preserved submarine landform assemblage has been produced. (a) Subglacial landforms include: overridden moraine ridges, mega-scale glacial lineations (MSGLs), other streamlined lineations, elongate drumlins and medial moraines, small ridges forming a complex boxwork or rhombohedral pattern, and meltwater-related eskers and channels. (b) Ice-marginal landforms include: large terminal moraines with debris flow lobes on their outer flanks and indentations on their inner sides, small transverse retreat moraines, and crater-like kettle holes. (c) Glacimarine features include: iceberg ploughmarks and an otherwise relatively smooth sedimentary seafloor produced by fine-grained debris rain-out. A schematic plan-view landform assemblage model for tidewater glaciers advancing into open-marine settings is developed. Arcuate terminal moraines marking the ice-advance limit provide a distinctive component. Submarine basin(s) exposed inside these moraine ridges when ice retreats contain suites of individual landforms, produced subglacially and ice-marginally, with a consistent order of timing of deposition and stratigraphic superposition. The new schematic model is compared with earlier models based on submarine landforms associated with surges in the more topographically constrained setting of Spitsbergen fjords. Differences include: (i) the overall arcuate shape of the open-marine assemblage; (ii) the indented ice-proximal sides of terminal moraine ridges; (iii) the fan-shaped pattern of streamlined lineations; (iv) crater-like kettle holes at the inner lateral margins of many submarine basins; (v) prominent systems of eskers and channels. Modern glaciological analogues from ongoing surges of ice caps in eastern Svalbard and Severnaya Zemlya provide contemporary observations of ice advance into open-marine settings, including heavily crevassed ice lobes with finger-like termini.

Past ice flow in Wahlenbergfjorden and its implications for late Quaternary ice sheet dynamics in northeastern Svalbard

Wahlenbergfjorden is a fjord situated in the western part of Nordaustlandet in northern Svalbard. It leads into the 400 m deep Hinlopen Strait located between Nordaustlandet and Spitsbergen. High-resolution multibeam bathymetric and sub-bottom data, as well as sediment cores are used to study the past extent and dynamics of glaciers in Wahlenbergfjorden and western Nordaustlandet. The submarine landform assemblage in Wahlenbergfjorden consists of landforms characteristic of subglacial, ice marginal and proglacial conditions. Glacial lineations indicate that Wahlenbergfjorden was occupied by streaming ice during the LGM and most likely acted as an ice stream onset zone. Westward ice flow in the fjord merged with the ice stream in Hinlopen Strait. Absence of ice recessional landforms in outer Wahlenbergfjorden suggests relatively fast deglaciation, possibly by flotation of the glacier front in the deeper parts of the fjord. The inner part of Wahlenbergfjorden and Palanderbukta are characterized by De Geer moraines, indicating episodic retreat of a grounded glacier front. In Palanderbukta, longer still stands of the glacier terminus resulted in the formation of larger terminal moraine ridges. The inner part of Wahlenbergfjorden was deglaciated prior to 11.3 ± 55 Cal. ka BP. The submarine landform assemblages in front of Bodleybreen, Etonbreen, Idunbreen, Frazerbreen and Aldousbreen confirm that these glaciers have surged at least once during the Holocene.

Assemblage of glacial and related landforms in the fjords of southern Chile

At 42–55° S (Fig. 1a), the fjords of southern Chile are one of the lowest-latitude and mildest regions in which glaciers reach the sea today (Dowdeswell & Vasquez 2013). The Andean ice caps and glaciers of the Darwin Cordillera in Tierra del Fuego are of high mass throughput with precipitation often metres per year and, to balance this, very high rates of surface melting. These ice masses either reach the sea at fjord heads or feed braided-river systems that flow into the fjords. Large volumes of meltwater and glacial sediment are therefore delivered to Chilean fjords either directly from subglacial streams beneath tidewater glaciers or indirectly by glacifluvial processes. At the Last Glacial Maximum (LGM) the Patagonian Ice Cap expanded to fill these fjords, which were re-occupied by ocean waters as deglaciation proceeded. Fig. 1. Sun-illuminated multibeam-bathymetric images of submarine landforms in the fjords of Chilean Patagonia. Acquisition system Atlas Fansweep. Frequency 200 kHz. Grid-cell size 20 m. ( a ) Location of study area (red box; map from GEBCO_08). ( b ) Terminal moraine ridge and other transverse ridges produced by Tempano Glacier, inner Iceberg Fjord. S, streamlined lineations. ( c ) Hummocky but otherwise largely flat seafloor beyond Pio XI Glacier in Eyre Fjord. H, hummocky glacial debris. ( d ) Swath-bathymetric image of 100 m high recessional moraine in Europa Fjord. ( e ) Glacifluvial delta in Iceberg Fjord fed from an associated braided river. ( f ) Glacifluvial delta in Bernardo Fjord, showing a braided river and the adjacent Bernardo Glacier. ( g ) Small fluvial delta in Eyre Fjord. Images modified after Dowdeswell & Vasquez (2013). We thank the Servicio Hidrografico y Oceanografico de la Armada de Chile (SHOA) for allowing use of their swath-bathymetric data. Many Chilean fjords have experienced tidewater-glacier advance during the cool Little Ice Age (approximately sixteenth–nineteenth centuries), followed by retreat over the past century …

Rhombohedral crevasse-fill ridges at the marine margin of a surging Svalbard ice cap

The ice cap of Austfonna in eastern Svalbard is the largest in the Eurasian Arctic at 8000 km2 and has about 200 km of marine-terminating ice cliffs (Dowdeswell et al. 2008). Several of its drainage basins are of surge type (Meier & Post 1969) and, between 1936 and 1938, one of these basins (Brasvellbreen; 1100 km2) increased its velocity rapidly and underwent an advance of about 20 km along a 30 km wide front (Schytt 1969). Since that time the ice-cap terminus has stagnated and retreated, losing mass by a combination of surface melting, thinning and iceberg production. Retreat has revealed several distinctive and well-preserved submarine landforms (Fig. 1) linked to this recent surge activity (Solheim & Pfirman 1985; Solheim 1991). Fig. 1. ( a ) Rhombohedral ridges and a terminal moraine ridge on the seafloor offshore of Brasvellbreen, an outlet of the Austfonna ice cap in eastern Svalbard. Image courtesy of the Norwegian Hydrographic Service (Permission no. 14/G754). Acquisition system Kongsberg EM1002. Frequency 97 kHz. Grid-cell size 3 m. The ridges are interpreted to have been formed by the filling of basal crevasses with deforming diamictic sediment. ( b ) Oblique aerial photograph of the surge and rapid advance of Brasvellbreen in 1938 (Photo S38-1958; courtesy of Norsk Polarinstitutt). ( c ) Location of study area (red box; map from IBCAO v. 3.0). ( d …

Annual moraine ridges in Tempelfjorden, Spitsbergen

Surging tidewater glaciers produce a characteristic landform assemblage with glacial lineations, networks of crevasse-fill ridges, large terminal moraine ridges and several recessional moraines, which often override glacial lineations (Solheim 1991; Ottesen et al. 2008). Submarine recessional moraines have also been mapped beyond several Svalbard tidewater glaciers and are interpreted to record an annual to semi-annual signal of glacial retreat during the quiescent phase of the surge cycle (Ottesen & Dowdeswell 2006; Ottesen et al. 2008). The moraine ridges probably form during winter stillstands or minor readvances of the glacier terminus (Boulton et al. 1996; Ottesen et al. 2008). Tunabreen is a tidewater glacier of surge type located in Tempelfjorden, Spitsbergen (Fig. 1e). It has surged three times since the Little Ice Age, in 1930, 1970 and between c. 2002 and 2005 (Forwick et al. 2010) producing large terminal moraines (Fig. 1a). During the latest surge, the glacier margin reached its maximum extent in 2004 and has since retreated about 1 km. Fig. 1. Multibeam-bathymetric images of Tempelfjorden, Svalbard. Image courtesy of the Norwegian Hydrographic Service (permission no. 13/G706). ( a ) Image of inner Tempelfjorden, superimposed on an aerial image from 2009 (Photo …

Skjoldryggen terminal moraine on the mid-Norwegian shelf

Terminal moraines are relatively large ridges of diamictic glacial debris produced at the outermost margins of past glaciers and ice sheets. Their identification on land is important in mapping the maximum extent of Quaternary ice sheets (e.g. Svendsen et al. 2004; Benn & Evans 2010). In marine environments where fast-flowing ice streams reach the shelf edge during full-glacial intervals, moraine ridges are not usually present and the seafloor is characterized by parallel-to-flow streamlined sediments (Ottesen & Dowdeswell 2009). Submarine terminal moraine ridges, by contrast, appear more typical of slower-flowing marine ice margins (Dahlgren et al. 2002; Dowdeswell & Elverhoi 2002; Dowdeswell et al. 2016). A very large ridge, about 150 km long and up to approximately 200 m high relative to the adjacent shelf, is located on the outermost part of the mid-Norwegian continental shelf edge between about 65° and 66° N (Fig. 1a). It is known as Skjoldryggen (‘skjold’ means ‘shield’ and ‘ryggen’ means ‘the ridge’ in Norwegian). Along most of its length, the ridge has a steeper offshore slope relative to …

Debris-flow lobes on the distal flanks of terminal moraines in Spitsbergen fjords

Terminal and recessional moraines formed at the margins of tidewater glaciers are often asymmetrical, with relatively steep ice-distal sides and lower-gradient ice-proximal slopes (e.g. Benn & Evans 2010; Dowdeswell & Vasquez 2013). Their ice-distal slopes, in particular, may be the locations of slope failure and the generation of debris flows that produce elongate lobes of sediment that flow down the distal moraine-ridge flanks. Glacier-derived diamictic sediment forms the major component of most moraine ridges, and debris flows derived from such material would also be expected to produce debrites of heterogeneous particle size and with abrupt lateral margins and terminations. In several Spitsbergen fjords (Fig. 1g), well-defined elongate lobes of sediment are found on the relatively steep (but usually <2°) ice-distal slopes of terminal moraine ridges (Fig. 1) (e.g. Boulton et al. 1996; Plassen et al. 2004; Ottesen & Dowdeswell 2006). The submarine crests of the terminal moraines are typically too shallow to be traversed by survey vessels, so the ridge crests themselves occur just beyond the swath coverage at the left side of each image in Figure 1 at water …

Monitoring data on ameliorative status of agrolandscape

Long-term monitoring data on the ameliorative status of soils in the agrolandscape of a terminal moraine ridge are given. The effect of agroclimatic factors and specific features of the agrolandscape of the experimental station on groundwater level and moisture content in soil horizons are shown. The differentiation of agroameliorative measures for optimizing water–physical soil properties in different parts of the agrolandscape is substantiated.

Paleoflood marks in sandur morphometry as the result of the glacier surge (NW Poland)

In the Pomeranian marginal zone of the last Pleistocene glaciation specific morphometric features are found. They represent indicators of surging events affecting the individual outlet glacier lobes of the Scandinavian Ice Sheet margin. They are assumed to have been active during the climate warming of the Weichselian glaciation decay. Many tunnel valleys deep-rooted in the proximal slopes of the terminal moraine ridge with incised gorges and wide extramarginal sandur fans spread from the mouths to the forefield. The relatively low relief intensity factor, the fluvioglacial sediments covering distal slopes of the terminal moraines and ‘washed out’ older forms may be considered as indirect evidence of outburst floods caused by a re-canalization of the subglacial drainage system. The morphometry of the palaeochannels in the gorge profiles are used to calculate estimates of extreme discharges (c. 5 × 103–105m3s–1).

Observations on terminal moraine-ridge formation during recent advances of southern Norwegian glaciers

Abstract The formation of terminal moraines dating from glacier advances during the A.D. 1990s was investigated at six temperate glaciers in the Jostedalsbreen and Jotunheimen regions of southern Norway. Morphological and sedimentological information was analysed and combined with detailed observations, photographic evidence, and length variation measurements. Bulldozing (pushing) of proglacial sediments was the predominant process at the low-lying glacier termini of the debris-free outlets of the Jostedalsbreen ice cap. Evidence for bulldozing includes the relocation and rotation of boulders and the presence of lichen-covered boulders in the distal slopes of moraines. Differences in moraine sedimentology between the individual sites are attributed to variations in the pre-existing material pushed up, rather than to specific processes. In Jotunheimen, several modes of moraine-ridge formation were active: dumping of supraglacial debris and the marginal freezing-on and subsequent melting-out of subglacial sediment slabs were more important than bulldozing at some sites and in some years. Low air temperatures in winter at the higher altitude glacier termini enabled freezing-on to occur. However, the forelands are below the lower limit of discontinuous permafrost and evidence of thrusting is absent. Whereas discrete terminal moraine ridges at Jostedalsbreen are related to (seasonal) advances, the less dynamic glaciers of Jotunheimen allow the accretion of successive ridges during consecutive years. No single regional mode of moraine formation is characteristic for southern Norway: several processes are involved depending on individual glacier morphology and dynamics, the glaciological regime, and environmental conditions (especially climate) on the glacier forelands. The importance of specific processes varies within and between glacier forelands. Thus, spatial and temporal variation and local individuality has to be taken into account in the interpretation of moraine-ridge formation. Similar variability is likely to have been characteristic of terminal moraines deposited during the “Little Ice Age” and earlier in the Quaternary.

Productivity of herbaceous stands of different ages under landscape conditions of a terminal moraine ridge

Yield formation of uneven-aged herbaceous stands under various weather and lanscape conditions is investigated in a multifactor experiment. It is shown that yield and adaptive properties of the stands depend in many respects on their age and climatic situation as well as on the properties of the landscape and soil environment.

The Late Devensian terminal moraine ridge at Garret Hill, Stiffkey valley, north Norfolk, England

SUMMARY Glacial stratigraphy and ice-marginal processes within the limit of the Late Devensian Glaciation in eastern England were investigated at Garret Hill, situated on the eastern flank of the Stiffkey valley, north Norfolk. Glacial sediments are divided into four lithofacies units. LFA-1 and 2 consist of chalk-rich diamicton and flint-rich outwash deposits, respectively. These extend beyond the Late Devensian ice-limit and are attributed to glaciation during the Middle Pleistocene. LFA-3 and 4 comprise a red diamicton and meltwater deposits that are equated to the Holkham Till and Ringstead Sand and Gravel respectively, deposited during the Late Devensian Glaciation. It is proposed that a terminal moraine ridge was formed during the Late Devensian Glaciation as a Scottish-sourced ice sheet flowed southwards along the western margin of the North Sea Basin. The moraine is identified by the distribution of ridges and hummocks that border the outcrop of Holkham Till. At Garret Hill, these landforms contain folded chalk-rich diamicton (LFA-1) and flint-rich outwash sediments (LFA-2) overlain by Holkham Till. This event is likely to have been accompanied by the formation of glacial lakes in the Stiffkey valley, impounded between the blocking ice sheet to the north and the Cromer Ridge to the south. The site is only the second site where the Holkham Till has been found overlying glacial deposits of Middle Pleistocene age.

Further glacial tills on Exmoor, southwest England: implications for small ice cap and valley glaciation

This paper discusses glacial deposits down valley of the Punchbowl cirque basin on Winsford Hill, Exmoor. Geomorphological mapping, lithostratigraphic logging and sedimentological analyses have differentiated basin floor landform assemblages lying down valley of the Punchbowl terminal moraine ridge to include: subglacial diamict, periglacial solifluctate and fluvial deposits. Local ice cover at some stage during the Quaternary appears to have been more extensive than hitherto believed, and most probably extended to a small ice cap on the broad plateau surface of Winsford Hill at just over 400 m OD. It is concluded that other plateau surfaces on Exmoor at similar altitudes may also have nurtured ice caps at certain times during the Quaternary. These findings further suggest that the long-held view of Dartmoor as an unglaciated upland region may need re-evaluating.

Geomorphology of the Gor Garang Glaciers, Himachal Pradesh, India

AbstractThe Gor Garung group of glaciers constitute an ice cover of over 4 km2 in a basin of 27 km2 area, lying in the Sutlej River catchment of the north–western Himalaya. This paper, the first record of these glaciers, their moraines and lakes observed in this area, is the result of mapping the glaciers and the pro–glacial field.An attempt has been made to utilize lichenometry for establishing relative antiquity of various terminal moraine ridges generated by these glaciers, and six groups have been determined.

Geomorphology of the Gor Garang Glaciers, Himachal Pradesh, India

Abstract The Gor Garung group of glaciers constitute an ice cover of over 4 km2 in a basin of 27 km2 area, lying in the Sutlej River catchment of the north–western Himalaya. This paper, the first record of these glaciers, their moraines and lakes observed in this area, is the result of mapping the glaciers and the pro–glacial field. An attempt has been made to utilize lichenometry for establishing relative antiquity of various terminal moraine ridges generated by these glaciers, and six groups have been determined.