Ice-sheet Events Research Articles

Iceberg Detection using Satellite Images

Chunks of ice present genuine risks for transport route and seaward establishments. Subsequently, there is a huge interest to limit them ideal and over tremendous regions. As a result of their autonomy of overcast cover and sunlight, satellite Synthetic Aperture Radar (SAR) pictures are among the favoured information hotspots for functional ice conditions and ice sheet events. The picture spatial goal for the most part utilized for chunk of ice observing changes between a couple and 100 m. Prepared SAR information are portrayed by dot clamour, which causes a grainy appearance of the pictures making the distinguishing proof of ice shelves amazingly troublesome. The techniques for satellite checking of hazardous ice developments, similar to ice shelves in the Arctic oceans address a danger to the security of route and monetary action on the Arctic rack. Along these lines, here we have thought of a thought of an application which distinguishes the Iceberg pictures utilizing satellite pictures and it is proposed by utilizing Convolutional Neural Networks (CNN) grouping.

The subglacial imprint of the last Newfoundland Ice Sheet, Canada.

The former Newfoundland Ice Sheet was situated on the fringes of the northeast Atlantic Ocean during the Wisconsinan glaciation (∼80–10 ka BP). Its geographic position indicates that it was likely to have been influenced by a number of external and internal forcing mechanisms including configuration changes in the Laurentide Ice Sheet with which it converged during the last glacial maximum, ice streams, changes in oceanic circulation and fluctuating sea levels. This makes Newfoundland a key location for investigating the dynamic response of ice sheets to these types of internal and external drivers. An established methodology for investigating ice sheet dynamics is to use the landform record to reconstruct the dynamic behaviour and configuration of the ice sheet. This provides a relative chronology of former ice sheet events during glacial cycles. A fundamental requirement of this approach is a detailed glacial geomorphology map that records the spatial distribution of individual subglacial bedforms across the former ice sheet bed. This paper presents a new subglacial bedform map of the Island of Newfoundland. It was produced as part of a mapping programme which used 10 m resolution Satellite Pour l'Observation de la Terre satellite imagery, Shuttle Radar Topography Mission and Canadian Digital Elevation Data. The map records the spatial distribution of ∼126,000 individually mapped glacial lineations and ribbed moraines and extends the number and spatial extent of each landform across the island. It is a new data set which has the potential to provide important insights into former ice sheet behaviour in this region.

Marine geophysical evidence for ice sheet extension and recession on the Malin Shelf: New evidence for the western limits of the British Irish Ice Sheet

Multibeam swath bathymetry and backscatter data collected as part of the Irish National Seabed Survey and Integrated Mapping for the Sustainable Development of Ireland's Marine Resource programmes is used to investigate the glacial geomorphology of the Malin Shelf. The data provides direct evidence that the former British Irish Ice Sheet was grounded as far out as the shelf break in this sector on more than one occasion. Drumlins on the outer shelf indicate the region was a zone of confluence where ice flowing onto the shelf from northwest Ireland converged with ice flowing across the shelf from western Scotland. Ice berg furrows located on the outer shelf record ice sheet break up by a calving event that may have been triggered by rising sea levels and northwest–southeast aligned moraines indicate the ice retreated north-eastwards across the shelf towards Scotland. The absence of direct dating control from moraines on the Malin Shelf precludes a definitive assessment of the timing of ice sheet events. However, consideration of the stratigraphic relationship of the glacial landforms on the shelf with age constrained ice sheet events in the wider region indicates that the former British Irish Ice Sheet reached the outer shelf in this region on at least two occasions during the last cold stage. Moraines that have been overprinted by drumlins may possibly belong to an early phase of glaciation that occurred c 45 ka B. This was subsequently followed by another episode of shelf extensive glaciation where converging ice flow from northwest Ireland and western Scotland reached the shelf break during the LGM that subsequently retreated from the shelf edge around 23 ka BP.

Stratigraphic Architecture and Sediment Facies of the Western Oak Ridges Moraine, Humber River Watershed, Southern Ontario*

The Oak Ridges Moraine in southern Ontario is aca. 160 km long east-west trending ridge of sand and gravel situated north of Lake Ontario. Study of the Oak Ridges Moraine in the Humber River watershed was undertaken to assess its role in the groundwater system of the buried Laurentian Valley. The Oak Ridges Moraine is interpreted to have been deposited in three stages. Stage I records rapid deposition from hyperconcentrated flows where tunnel channels discharged into a subglacial lake in the Lake Ontario basin. Low-energy basin sedimentation of Stage II was in a subglacial and ice-contact setting of a highly crevassed ice sheet. Stage III sedimentation is characterized by rapid facies changes associated with esker, subaqueous fan, and basinal sedimentation. Detailed sediment analysis challenges the concept that the Oak Ridges Moraine was deposited principally from seasonal meltwater discharges, climatic modulated ice-marginal fluctuations, or in an interlobate position. Instead it is interpreted to have formed in response to late-glacial ice sheet events associated with subglacial meltwater ponding, episodic and catastrophic subglacial meltwater discharge, and subsequent seasonal meltwater discharge. The moraine probably formed as the glacial-hydraulic system re-equilibrated to the presence of a thinned, grounded ice shelf and a subglacial lake in the Lake Ontario basin.

Direct constraints on Antarctic Peninsula Ice Sheet grounding events between 5.12 and 7.94 Ma

How has the Antarctic Ice Sheet responded to or influenced global climate change? This simple question has been difficult to address because the long‐term records of the ice sheet's fluctuations are poorly constrained with geologic data from Antarctica. Thus studies to date have not convincingly established how specific Antarctic Ice Sheet events correlate with climatic, eustatic, or other phenomena known from low‐latitude and deep‐sea records. This study focused on documenting the direct record of ice sheet advance and retreat to the Antarctic Peninsula's shelf edge. On the peninsula's outer shelf, seismic reflectors interpreted to be subglacial unconformities were correlated with published results from Ocean Drilling Program Leg 178. Lithologic and chronologic control at two drill sites provided ground truth for the seismic interpretation and the timing of the Antarctic Peninsula Ice Sheet grounding events. This synthesis showed that grounded ice advanced to the shelf edge on at least 12 occasions between 5.12 and 7.94 Ma.

Glaciomarine deposition around the Irish Sea basin: some problems and solutions

AbstractReconstructing the depositional processes and setting (marine or terrestrial depositional environment) of late Devensian age glacigenic sediments around the Irish Sea basin (ISB) is critical for developing an all‐embracing and consistent glacial model that can account for all observed field evidence. Identifying episodes of marine and terrestrial glacial deposition from field data is considered the first step in achieving this goal. Criteria for distinguishing marine and terrestrial glacial environments in the ISB include the geomorphology, sedimentology and faunal content (biofacies) of the associated deposits.Exposures of glacigenic sediments around the ISB are very diverse in terms of their morphosedimentary characteristics and associated biofacies, and thus inferred depositional processes and setting. Possible reasons for the diverse geological record include the differing geometry of eastern and western ISB coasts, time‐transgressive ice retreat, and differential land rebound effects as a result of forebulge collapse and neotectonics. Poor geochronometric control on ice sheet events has not helped the correlation of ISB events with glacial and climatic events elsewhere. Future investigations of glacial sites around the ISB should use an integrated methodological approach involving a range of geomorphological, sedimentary and biofacies data, and dating control where possible. This will help in developing a more precise and holistic late Devensian glacial model that is constrained rigorously by field geological evidence. Copyright © 2001 John Wiley & Sons, Ltd.

Glaciomarine deposition around the Irish Sea basin: some problems and solutions

Reconstructing the depositional processes and setting (marine or terrestrial depositional environment) of late Devensian age glacigenic sediments around the Irish Sea basin (ISB) is critical for developing an all-embracing and consistent glacial model that can account for all observed field evidence. Identifying episodes of marine and terrestrial glacial deposition from field data is considered the first step in achieving this goal. Criteria for distinguishing marine and terrestrial glacial environments in the ISB include the geomorphology, sedimentology and faunal content (biofacies) of the associated deposits. Exposures of glacigenic sediments around the ISB are very diverse in terms of their morphosedimentary characteristics and associated biofacies, and thus inferred depositional processes and setting. Possible reasons for the diverse geological record include the differing geometry of eastern and western ISB coasts, time-transgressive ice retreat, and differential land rebound effects as a result of forebulge collapse and neotectonics. Poor geochronometric control on ice sheet events has not helped the correlation of ISB events with glacial and climatic events elsewhere. Future investigations of glacial sites around the ISB should use an integrated methodological approach involving a range of geomorphological, sedimentary and biofacies data, and dating control where possible. This will help in developing a more precise and holistic late Devensian glacial model that is constrained rigorously by field geological evidence. Copyright © 2001 John Wiley & Sons, Ltd.

Stochastic resonance in the North Atlantic

Large, abrupt changes between warm and cold modes of North Atlantic climate exhibit spectral power at ∼1500 years, yet some climatic changes were linked to outburst floods and other events that are unlikely to have been truly periodic. We hypothesize that a weak periodic forcing has combined with “noise” from ice sheet‐related events to cause the observed mode switches. This stochastic resonance hypothesis predicts a recurrence pattern between warmings that is distinct from the predictions of simple periodic and stochastic models and at least some other models. The ice isotopic data from central Greenland ice cores are consistent with the stochastic resonance hypothesis but not with other models we have tested. We thus support arguments for the existence of a periodicity of ∼1500 years in the North Atlantic climate system and for the importance of ice sheet events in forcing North Atlantic changes.