Marine Landforms Research Articles

Identification of Marine Landforms as a Form of Coastal Area Management in Pangandaran District

Changes in marine landforms in coastal areas are relatively rapid and need to be analyzed to determine environmental management policies. Complex marine landforms are found in the coastal areas of Pangandaran Regency and have strong pressure to fulfill community activities, not only for local communities but also for outside communities. Basically, community activities are adapted to regional environmental conditions. The aim is to optimize the potential of natural resources and minimize environmental degradation, but in reality, this has not been fully implemented. The method used in this research is a descriptive method using a field survey approach. Marine landforms resulting from the accretion process in the Pangandaran coastal area are spit landforms, aeolian-marine sedimentation in the form of coastal dunes, fluvio-marine sedimentation in the form of estuaries and alates, organic-marine landforms and white sand beaches associated with reefs. The landforms resulting from erosion are Cliffs, notches, wave-cut platforms, stacks, and stumps. The impact of landforms resulting from sedimentation in the Pangandaran coastal area is mainly spit landforms that cover river mouths and the occurrence of flooding, puddles, and even accumulation of organic waste, landforms resulting from erosion, the impact of which is the decline of the coastline accompanied by avalanches of material towards the sea, especially on beaches that have non-resistant rocks such as sedimentary rocks and alluvial deposits. Management of the Pangandaran coastal environmental area must be carried out in an integrated manner, land buritan (hinterland), which has steep slopes and resistant rock, is designated as limited production land, and the development of the spit at the river mouth is made into a jetty, and the beach has beach cups waves with rip currents and water bathymetry. -10 meters above sea level, a wave-protecting wall must be built, and the coastal border area must be used as vegetative-based conservation land.Keywords: Marine landforms, Coastal Management, Pangandaran

Zonasi Bencana Abrasi Pantai Sappoang Kabupaten Polewali Mandar

This research uses a formula approach. In formula has several variables. The variables in this research are tidal, ocean current speed and direction, wave height and wave period, type of geological structure of the coast and sediment grain size materials, the slope of the beach and coastline direction, wind speed and direction. The number of samples or observation points at 27, with interval distance every point is 200 m. The results of the research were analyzed in the waves of the type formula and determinants of abrasion and sedimentation. Sappoang Beach is one of the marine landforms are more specifically known as a land form bar (deposition of sand along the coast). Conditions beach located around the mouth of the river to the beach physical differences that are in the basin area (central coast), where the force of the waves, and the flow velocity at the beach slope basin area beaches have greater value when compared to the coastal areas near the mouth river. The results showed that there are three conditions in Sappoang Beach beaches of different areas of research currently conducted (the west wind), like sedimentation area, balanced and abraded. Abraded zone and sedimentation zone is more dominant than the beaches that are stable. This is more significant because at the time of measurement, the wind is blowing west wind, given the quantity of variables measuring the higher the coast, so the coastal zone is increasing abraded.

Pedogeomorphology and weathering at Snow Island, Maritime Antarctica

Despite progress in the last decade on periglacial geomorphology and permafrost research in Antarctica, many areas in Maritime Antarctica remain unsurveyed. This study aimed to identify and describe the main periglacial landforms of President Head Peninsula, at Snow Island, Maritime Antarctica, with emphasis on the relationships between soils, landforms and lithology. We identified and mapped landforms and their physiographic aspects at 1:15,000 scale using Sentinel-2 satellite image (10 m spatial resolution) and georeferenced using portable GPS. Morphological, physical, chemical, micromorphological and mineralogical properties of selected soils were also analyzed. Seventeen types of landforms were mapped (glacial, glaciofluvial, tectonics and structural, periglacial, and marine landforms), whose complexity of geomorphic features is explained by the diversity of morphogenetic processes and lithological diversity. Three distinct geomorphological domains were identified (proglacial, paraglacial, and periglacial). The paraglacial domain is more dynamic and presents immature or poorly developed soils. The periglacial domain has many rocky outcrops, interspersed with Holocene beaches and vegetated marine terraces. Landforms associated with gelifluction, patterned ground and permafrost were only observed on the upper plateaus of the periglacial domain. No soil formation were observed in the proglacial domain.

Geomorphology of the seafloor north east of the Maltese Islands, Central Mediterranean

ABSTRACT This paper presents a geomorphological map of the seafloor north east of the Maltese Islands (Central Mediterranean) at a scale of 1:50,000. The map was compiled following the integration, analysis and interpretation of several high-resolution seafloor bathymetry datasets. Several structural features, coastal and marine landforms and anthropogenic features have been mapped. Most of the mapped submerged landforms – including fluvial, gravity-induced and karst landforms – appear to have been formed during the sea-level lowstand of the last glacial cycle. The map provides valuable insights on the submerged landscape of the Maltese Islands and its evolution since the Last Glacial Maximum.

Surging glaciers in Scotland

ABSTRACT Glacier surges are cyclic oscillations of velocity and mass resulting from internal dynamic instabilities. For surge-type glaciers, cycles of advance and retreat are decoupled from climate forcing, so it is important to consider the possibility that former glaciers may have been surge-type when making climatic inferences from their dimensions and chronologies. In this paper, climatic and glacier geometric data are used to show that Scotland was likely the location of a surge cluster during the Loch Lomond Stade (∼12.9–11.7 ka), with high probabilities of surging for outlets of the West Highland Icefield and the larger glaciers in the Inner Hebrides and Northern Highlands. Terrestrial and marine landforms consistent with surging occur in all of these areas, and it is proposed that surge-type glaciers existed on the Islands of Skye and Mull, in the Northern Highlands, and in a ‘surging arc’ along the western, southern and south-eastern margins of the West Highland Icefield. The possibility that surge-type glaciers were widespread in Scotland during the Loch Lomond Stade offers a fresh perspective on some long-standing issues, including the relationship between style of deglaciation and climate change, the climatic significance of glacial chronologies, palaeoclimatic reconstructions, and the interpretation of numerical model results.

Geomorphological Evolution of the Patagonian Coast Surrounding the Golfo Nuevo (Chubut, Argentina) during Late Quaternary: Overview and New Proposal

Bunicontro, M.P. and Marcomini, S.C., 2021. Geomorphological evolution of the Patagonian coast surrounding the Golfo Nuevo (Chubut, Argentina) during Late Quaternary: Overview and new proposal. Journal of Coastal Research, 37(3), 528–543. Coconut Creek (Florida), ISSN 0749-0208.The main contribution of this paper is a new interpretation of the geomorphological evolution of the North Patagonian coast surrounding the Golfo Nuevo from Mid-to-Late Pleistocene until present. The proposed model shows how continental and marine landforms evolved during the Late Quaternary. According to this, the Golfo Nuevo depression formed during the Middle Pleistocene (>130 ka) above previous fluvial terraces, which are attributed to different stages of the Chubut river. Several pediment types and levels were also identified: (1) flanking pediment (level 1) associated with an ancient fluvial valley; (2) convergent pediment related to a previous depression of Golfo Nuevo (level 2), both assigned to Middle Pleistocene; and (3) a littoral pediment (level 3) linked to a Holocene highstand level. The height and position of accretion marine terraces are discussed, in addition to their previous dating. It can be assumed that Golfo San Matías was flooded twice as a consequence of marine transgressions (marine isotopic stage [MIS] 5 and MIS 1). Likewise, Golfo Nuevo and Golfo San José were affected only once, during the maximum Holocene transgression (MIS 1). This paper highlights the importance of reconstructing the geomorphological evolution of a coastal area of the Patagonia as a result of a combination of changes linked to sea-level variations (mainly associated with glacio-eustasy) and climate, paleo-shorelines records, and continental landforms through Late Quaternary. The proposed geomorphological model can be considered a novelty because of the complex integration of continental and marine landforms and the study of their relative relation.

Late Miocene - Quaternary forearc uplift in southern Peru: new insights from 10Be dates and rocky coastal sequences

We explore the coastal morphology along an uplifting 500 km-long coastal segment of the Central Andes, between the cities of Chala (Peru) and Arica (Chile). We use accurate DEM and field surveys to extract sequences of uplifted shorelines along the study area. In addition, we consider continental pediment surfaces that limit both the geographical and vertical extent of the marine landforms. We establish a chronology based on published dates for marine landforms and pediment surfaces. We expand this corpus with new 10Be data on uplifted shore platforms. The last 12 Ma are marked by three periods of coastal stability or subsidence dated ~12-11 Ma, ~8-7 Ma and ~5–2.5 Ma ago. The uplift that accumulated between these stability periods has been ~1000 m since 11 Ma; its rate can reach 0.25 mm/a (m/ka). For the last period of uplift only, during the last 800 ka, the forearc uplift has been accurately recorded by the carving of numerous coastal sequences. Within these sequences, we correlated the marine terraces with the sea level highstands (interglacial stages and sub-stages) up to MIS 19 (790 ka), i.e., with a resolution of ~100 ka. The uplift rate for this last period of uplift increases westward from 0.18 mm/a at the Peru-Chile border to ~0.25 mm/a in the center of the study area. It further increases northwestward, up to 0.45 mm/a, due to the influence of the Nazca Ridge. In this study, we document an unusual forearc cyclic uplift with ~4 Ma-long cycles. This periodicity corresponds to the predictions made by Menant et al. (2020) based on numerical models, and could be related to episodic tectonic underplating (subducting slab stripping) beneath the coastal forearc area.

Salinity of paddy field in main landforms in Indramayu Regency, West Java

One of the main problems of paddy field in Indramayu is the high level of salinity. Paddy fields in Indramayu Regency are located around the North Coast. This area is dominated by the alluvial, fluvio-marine, and marine landforms groups. This study aims to examine the relationship between soil salinity and the type of landform. A total of 102 soil samples on paddy soils were taken and analyzed in the laboratory to obtain soil salinity data. The average of soil salinity value in each landform was compared with one another. Several litho-sequent transects were constructed to observe the pattern of salinity distribution and two soil profiles were observed to confirm the soil forming material. The soils in the marine landform group had the highest salinity, followed by the fluvio-marine and alluvial group, with a mean value was 390.6 mg.L-1, 141.0 mg.L-1, and 61.9 mg.L-1, respectively. The salinity of soils developed from marine deposit is higher than alluvium deposit. The closer distance to coastline makes the possibility of higher sea water intrusion, causing higher soil salinity. The landform approach in estimating soil salinity level is very useful, making it easier to find effective land management to reduce negative impacts on paddy field.

Erosive features caused by a Magellanic penguin (Spheniscus magellanicus) colony on Martillo Island, Beagle Channel, Argentina

An active Magellanic penguin (Spheniscus magellanicus) colony has been established on Martillo Island, Beagle Channel (54°54´26” S; 67°22´58” W) since 1976. It is located in remnants of eroded drumlins placed in both ending and joined by gravel terraces of glaciofluvial and marine origin. Forest patches occupy the eastern side of the island while most of the island is covered by bushes, tussocks and grasses. This paper presents penguins as bio-erosion agents on glacial and marine landforms. An analysis of multiple criteria surveyed in the field was performed, using Quantum GIS® 3.2.1 with remote sensing images and a digital model terrain of 12 m resolution. The morphometric data and multicriterial evaluation were collected during 2016-2017 austral summer. Soils and sediments of each landform (drumlin, glaciofluvial terrace, raised beach and beach) were sampled for particle size analysis, to determine if there is any relationship between the morphometric parameters of the cave and the sediments. Four bio-erosion classes were defined based on the erosion features observed in the field. “Moderate” was the prevailing erosion class recorded, in the E-NE part of the island. Bio-erosion features are mainly developed on the N facing slope of the east of the island, where a natural gully drains rainfall water, and over the glaciofluvial and marine terrace surfaces. Erosive features such as caves and bridges are mainly developed in silty drumlins. Pedestals are developed on bare soils and tussocks. Trails and cracks were also described as bio-erosion. No erosive features were recorded in the W part of the island. The bio-erosion map is one of the inputs for environmental degradation analysis and population dynamic research which is being done in the Magellanic penguin colony on Martillo Island, Beagle Channel.

Terrestrial and Marine Landforms along the Cilento Coastland (Southern Italy): A Framework for Landslide Hazard Assessment and Environmental Conservation

This study shows the terrestrial and marine landforms present along the Cilento coast in the southern part of the Campania region (Italy). This coast is characterized by the alternation of bays, small beaches, and rocky headlands. In the adjacent submerged areas, there is a slightly inclined platform that has a maximum width of 30 km to the north, while it narrows in the south to approximately 6 km. A wide variety of landforms are preserved in this area, despite the high erodibility of the rocks emerging from the sea and the effects of human activities (construction of structures and infrastructures, fires, etc.). Of these landforms, we focused on those that enabled us to determine Quaternary sea-level variations, and, more specifically, we focused on the correlation between coastal and sea-floor topography in order to trace the geomorphological evolution of this coastal area. For this purpose, the Licosa Cape and the promontory of Ripe Rosse located in northern Cilento were used as reference areas. Methods were used that enabled us to obtain a detailed digital cartography of each area and consequently to apply physical-based coastal evolution models. We believe that this approach would provide a better management of coastal risk mitigation which is likely to become increasingly important in the perspective of climate change.

Coastal landforms of “Meso-Afro-American” and “Neo-American” landscapes in the periglacial South Atlantic ocean: With special reference to the clast orientation, morphology, and granulometry of continental and marine sediments

Coastal landforms of “Meso-Afro-American” and “Neo-American” landscapes in the periglacial South Atlantic ocean: With special reference to the clast orientation, morphology, and granulometry of continental and marine sediments

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.

Coastal eolian landforms and sea level fluctuations

This paper is dedicated to correlation of the formation of coastal marine landforms with sea level fluctuations and climate changes in the last millennium using the southeastern Baltic region as an example. The morphological analysis of spits and historical evidence reveal three sea level oscillations in its evolution. It is shown that the sea level rise against the background of the sandy material excess in the coastal zone and optimum angle of the prevailing land-directed wind are the main factors responsible for accumulation of the thickest sandy formations. The recent climate warming and related sea level rise provoke global destabilization of coastal dune massifs.

Near-surface deposits and hillslope evolution of the Adriatic piedmont of the Central Apennines (Feltrino Stream basin and minor coastal basins, Abruzzo, Italy)

This work presents a geomorphological map of the Feltrino Stream basin and minor surrounding coastal basins (scale 1:20,000), located in the south-eastern Abruzzo area (Central Italy), across the Adriatic piedmont of the Maiella massif (Central Apennines). This geomorphological mapping is focused on near-surface deposits and hillslope evolution analysis and includes three sections: main geomorphological map; orography and hydrography; and geomorphological models of hillslope evolution.In the study area, landforms and continental near-surface deposits are mainly linked to slope and fluvial processes, even though structural, marine, and anthropogenic landforms are also present. The mapping is primarily focused on near-surface deposits and landforms related to the evolution of hillslopes, resulting from the combination of tectonic (regional uplift) and surface processes. At a local scale, it can contribute to an understanding of the causes, mechanisms, and consequences of the changes of landforms and hillslopes and help solve engineering geomorphological problems. Finally, it is also a tool for the assessment of geomorphological hazards in landscapes characterized by widespread near-surface deposits and intense and rapid geomorphological processes, as well as a tool for land management.

Large-scale carbonate platform development of Cay Sal Bank, Bahamas, and implications for associated reef geomorphology

The Bahama Archipelago consists of an arcuate chain of carbonate platforms. Average water depths on the platform-tops, such as the Great Bahama Bank (GBB), are typically 10m or less, with coral reef-rimmed margins, thick sediment accumulations, and the frequent occurrence of islands. There are, however, exceptions. For example, Cay Sal Bank (CSB), a little studied detached Bahamian carbonate platform with depths ranging from 30 to 7m, is only slightly deeper than the GBB, but devoid of islands, lacks platform-margin coral reefs and holds little sediment on the platform-top; the platform is incipiently drowned. CSB is interesting as it is conspicuously larger (6000sq.km) than other incipiently drowned platforms in the region, such as Serranilla Bank (1100sq.km) and the Cat Island platform (1500sq.km). Field and remote sensing data are assembled to provide insight into the sedimentology and geomorphology of the CSB. The influence of ocean climate, regional hydrodynamics, and Holocene flooding history are investigated to understand why platform-margin coral reef growth on CSB has been unable to keep pace with Holocene sea-level rise. A decade of regional sea-surface temperature data for the Bahamas report CSB to be situated in the same ocean climate regime as GBB. Temperature cannot explain the platform's different morphologies. The Florida Current has been evoked as a possible reason for the immature development of platform-top processes on the CSB, but numeric modeling suggests its influence to be restricted to the deep flanks of the bank. Further, sediment distribution on CSB, including infill patterns of karst depressions, suggest trade winds (easterlies) to drive platform-top hydrodynamics. By assembling a satellite-derived bathymetry map, it can be shown that CSB flooded earlier and at relatively higher rates of Holocene sea-level rise than its neighboring platforms. Flooding history is identified as the most feasible explanation for the atypical morphology of the CSB. By contrasting the present-day morphology of the CSB and the GBB, the work emphasizes how subtle differences in relative sea-level history can influence the growth of platform-margin coral reefs, features that in turn can conspire to set even closely neighboring carbonate platforms on divergent paths with regard to the development of marine landforms. This insight is relevant to interpreting the morphological diversity of carbonate platforms in the modern ocean and in the rock record.

Geomorphological map of the Tremiti Islands (Puglia, Southern Adriatic Sea, Italy), scale 1:15,000

This paper describes the Geomorphological map of the Tremiti Islands (Puglia, Southern Adriatic Sea, Italy), scale 1:15,000. The Tremiti Islands, located north of Gargano promontory's coast, are part of a complex geological area within the Adriatic basin, facing the junction between the central and southern Apennines. This area is well known for Neogenic-Quaternary stratigraphic, tectonic and seismologic aspects and is crucial for the definition of Late Quaternary Adriatic basin evolution. The map is the result of a geomorphological study carried out on the islands and the inner continental shelf around them. This study incorporates: (1) field recognition of Quaternary continental deposits and geomorphological mapping, supported by radiometric dating, focused on the morpho-lithostratigraphic correlation of deposits among the different islands and the recognition of landforms that controlled landscape evolution; (2) bathymetric analysis; (3) geomorphological analysis of data from a side scan sonar survey, focused on the recognition of the main submerged landforms, from the coastline down to about 70 m b.s.l.; and (4) scuba-dive geomorphological survey, for improving analysis of geophysical data with direct observations. The study outlines a complex geological and geomorphologic setting. Despite the small size of the islands, the Quaternary continental succession of the archipelago is characterized by widespread deposits, a result of slope, fluvial and aeolian environments. The landforms of the islands are related to karst, fluvial, marine, and gravitational processes. The inner continental shelf features marine and coastal landforms, but also tectonic, fluvial, karst, and slope landforms. The correlation of the below sea-level geomorphological features with landforms and deposits of above sea-level areas, has provided a contribution to the reconstruction of Late Quaternary landscape and geomorphological evolution, as the result of tectonics, sea-level fluctuations and marine, coastal, and continental geomorphological processes.

The Kaali crater field and other geosites of Saaremaa Island (Estonia): the perspectives for a geopark

The Kaali crater field and other geosites of Saaremaa Island (Estonia): the perspectives for a geoparkThe Island of Saaremaa in Estonia offers highly spectacular geological features that belong to the most interesting in the Baltic Sea area. A unique geological monument on the island is the Kaali meteorite-crater field, formed by nine meteorite impacts. There are also attractive coastal cliffs, huge erratics, alvars (limestone areas covered by a very thin soil) and well-developed glacial and marine landforms. Limestone cliffs and shingle beaches abound with Silurian fossils and offer great opportunities to fossil collectors. The island is a prospective geopark. During the past few years, the geology of the island has become an intensely studied object of Estonian and Polish geologists.

Recuperated-OSL dating of quartz from Aegean (South Greece) raised Pleistocene marine sediments: current results

The purpose of this work is to provide an OSL dating framework for raised marine sequences in the South-West coast of Greece during Upper Quaternary. Paleontological investigations and Geographic Information System (GIS) analysis on elevated marine landforms have proved that a record of uplift and eustacy exists in South Greece since the Early Pleistocene (∼1.6 Ma). Hereby, we test the suitability of the SAR methodology for recuperated-OSL (Re-OSL), proposed by Wang et al. (2007), on coarse-grained quartz aliquots from emerged nearshore outcrops. Protocol's performance is examined on the basis of signal characteristics, dose response, sensitivity changes, recovery of known doses and Re-OSL bleachability to sunlight. The accuracy of the Re-OSL dates calculated for natural samples is also discussed.

A more precise radiocarbon age for an 8 m post-glacial sea-level stand at Cow Head, Newfoundland.

Brookes and Stevens (1985) reported a conventional radiocarbon date of 8250 ± 320 BP (d13C = +1.0 per mil; GSC – 3433 [2s error]; Blake (1986), p. 5; normalized to 8634 ± 320 BP) on three paired valves of Hiatella arctica (Linne) occupying cavities bored by them in limestone breccia at 6 m asl, at Cow Head, Newfoundland, on the Gulf of St. Lawrence (49°55’N; 57°48’W). Over the bored rock surface the beach-ridged surface of nearshore gravel relates to a sea-level stand at 8 m. This terrace is prominent locally, eroded across resistant Cambrian– Ordovician carbonates, as at Lower Head, which encloses Shallow Bay northward (Brookes and Stevens 1985, Fig.1). As mentioned in the original paper, two other shell occurrences in coastal cliffs along this shore have similar conventional 14C dates, and are associated with emerged marine landforms with elevations falling on a plane rising gently northwards, from 6 m asl at Western Brook, 10 km south (8340 ± 150 BP, GSC 1763 [no d 13C determined]), through the Cow Head – Lower Head features, to Parsons Pond, 13.5 km north (GSC – 1762, 8650 ± 150 BP [no d 13C determined]). At the latter site, Grant (in Lowdon et al. 1977, p. 3) reported an emerged marine foreland terraced at 13 m, 8 m, and 5 m asl. A feature at closer to 11 m would be expected there in this projection. A more precise AMS radiocarbon age has been obtained on a fragment of one Hiatella shell at 6 m asl on the same bored outcrop at Cow Head, 8960 ± 25 BP (d13C -1.4 per mil) (UCIAMS – 44422 [normalized to 9382 ± 25]. After normalization and subtraction of an estimated marine reservoir age of 530 years, averaged from values given for northern and southwestern Gulf of St. Lawrence in Dyke et al. (2003), this age calibrates to 10 599 ± 35 cal yr BP (Fairbanks et al. 2005). Such a relative sea-level stand, which includes the geomorphic and taphonomic contexts at Cow Head, and the similar context at Western Brook, and possibly at Parsons Pond, over a coast-wise distance of 23.5 km, could be expected to apply more widely along this shore, although there is no sufficiently detailed survey. The sea-level stand may have been due to (i) regional climatic deterioration sufficient to cause significant increase in glacial loading, briefly slowing isostatic uplift to the same rate as ocean-level rise; (ii) briefly increased glacial melting on a regional or wider scale, causing ocean-level to rise at the same rate as isostatic uplift; or (iii) briefly increased seaice activity which eroded the bedrock surface, destroying the Hiatella colony, and increasing the supply of inshore gravel to blanket the shore platform so formed. The calibrated age of the shells at Cow Head, 10599 ± 35 cal yr BP, is at the upper end of the range of calendar ages determined for a climatic cooling in evidence at ten localities in and around the Gulf of St. Lawrence (Brookes and Grant, in press). Three of these contexts represent glacier stillstand or readvance – along the 700 km Quebec North Shore Moraine System (Dubois and Dionne 1985), and in small highland ice caps in the northern Long Range of Newfoundland (Waitt 1981), and in the Cape Breton Highlands (Grant 1994). The age limits of this cooling have yet to be determined, but its effects, nevertheless, would have been felt in increased seaice activity, possibly accelerating coastal erosion (iii, above). Considering the proximity of the retreating margin of the Laurentide Ice Sheet, retardation of isostatic uplift along this coast of the Goldthwait Sea by ice readvance or stillstand (i, above) is a possibility worthy of geophysical attention.

Revision of the NW Laurentide Ice Sheet: implications for paleoclimate, the northeast extremity of Beringia, and Arctic Ocean sedimentation

For the past half-century, reconstructions of North American ice cover during the Last Glacial Maximum have shown ice-free land distal to the Laurentide Ice Sheet, primarily on Melville and Banks islands in the western Canadian Arctic Archipelago. Both islands reputedly preserve at the surface multiple Laurentide till sheets, together with associated marine and lacustrine deposits, recording as many as three pre-Late Wisconsinan glaciations. The northwest corner of Banks Island was purportedly never glaciated and is trimmed by the oldest and most extensive glaciation (Banks Glaciation) considered to be of Matuyama age (>780 ka BP). Inside the limit of Banks Glaciation, younger till sheets are ascribed to the Thomsen Glaciation (pre-Sangamonian) and the Amundsen Glaciation (Early Wisconsinan Stade). The view that the western Canadian Arctic Archipelago remained largely ice-free during the Late Wisconsinan is reinforced by a recent report of two woolly mammoth fragments collected on Banks and Melville islands, both dated to ∼22 ka BP. These dates imply that these islands constitute the northeast extremity of Beringia. A fundamental revision of this model is now warranted based on widespread fieldwork across the adjacent coastlines of Banks and Melville islands, including new dating of glacial and marine landforms and sediments. On Dundas Peninsula, southern Melville Island, AMS 14C dates on ice-transported marine molluscs within the most extensive Laurentide till yield ages of 25–49 ka BP. These dates require that Late Wisconsinan ice advanced northwestward from Visount Melville Sound, excavating fauna spanning Marine Isotope Stage 3. Laurentide ice that crossed Dundas Peninsula (300 m asl) coalesced with Melville Island ice occupying Liddon Gulf. Coalescent Laurentide and Melville ice continued to advance westward through M'Clure Strait depositing granite erratics at ≥235 m asl that require grounded ice in M'Clure Strait, as do streamlined bedforms on the channel floor. Deglaciation is recorded by widespread meltwater channels that show both the initial separation of Laurentide and Melvile ice, and the successive retreat of Laurentide ice southward across Dundas Peninsula into Viscount Melville Sound. Sedimentation from these channels deposited deltas marking deglacial marine limit. Forty dates on shells collected from associated glaciomarine rhythmites record near-synchronous ice retreat from M'Clure Strait and Dundas Peninsula to north-central Victoria Island ∼11.5 ka BP. Along the adjacent coast of Banks Island, deglacial shorelines also record the retreat of Laurentide ice both eastward through M'Clure Strait and southward into the island's interior. The elevation and age (∼11.5 ka BP) of deglacial marine limit there is fully compatible with the record of ice retreat on Melville Island. The last retreat of ice from Mercy Bay (northern Banks Island), previously assigned to northward retreat into M'Clure Strait during the Early Wisconsinan, is contradicted by geomorphic evidence for southward retreat into the island's interior during the Late Wisconsinan. This revision of the pattern and age of ice retreat across northern Banks Island results in a significant simplification of the previous Quaternary model. Our observations support the amalgamation of multiple till sheets – previously assigned to at least three pre-Late Wisconsinan glaciations – into the Late Wisconsinan. This revision also removes their formally named marine transgressions and proglacial lakes for which evidence is lacking. Erratics were also widely observed armouring meltwater channels originating on the previously proposed never-glaciated landscape. An extensive Late Wisconsinan Laurentide Ice Sheet across the western Canadian Arctic is compatible with similar evidence for extensive Laurentide ice entering the Richardson Mountains (Yukon) farther south and with the Innuitian Ice Sheet to the north. Widespread Late Wisconsinan ice, in a region previously thought to be too arid to sustain it, has important implications for paleoclimate, ice sheet modelling, Arctic Ocean ice and sediment delivery, and clarifying the northeast limit of Beringia.