The aim of this report is to describe the deglaciation in an area on west Greenland in the vicinity of Kangerlussuaq. To do this, the geomorphological landforms were mapped by studying areal photographs and by a two week field study where key areas were examiend. The landforms were transferred to a map using ArcGis and each key area were interpreted.The majority of the geomorphological formations were formed during the last deglaciation and consists of morain ridges, kettle topography in both till and glacifluvium, glacifluvial deltas, two fossil sandurs, and lateral terraces. Based on key areas and an inversion model a geomorphological map was created to illustrate the deglaciation, using the least complex explanation of the genesis of the landforms. The results show that the ice played a major role by damming lakes which enabled formation of many meltwater chanels and delta formations on higher elevations. The morain ridges and lateral terraces showed the extent of the ice margin during the halts in the ice retreat. The deglaciation was dated with help from earlier studies and the conclusion was that the deglaciation started between 7900 and 6700 yr BP. And the area was free from ice 7100-6500 yrs BP.

The area studied is part of Wester Ross, north-west Scotland, and includes the Applecross Peninsula and the land to the east between Strathcarron and Glen Torridon. Mapping of glacial landforms involved study of aerial photographs and subsequent field work. Evidence was found for the existence of two ice caps and five separate coire glaciers during the Loch Lomond Readvance, their various termini being represented today by clear lateral and end moraines at fourteen out of twenty-five locations. In nine cases, multiple lateral and/or end moraines suggest fluctuation of these ice margins during the Stadial maximum. An earlier stage of glaciation not related to the Late-Devensian ice-sheet maximum is represented by a single moraine and glacial striae. It is believed that this substage probably occurred between 18,000 and 14,000 years ago. Former sea-level changes were investigated by accurate mapping and instrumental levelling of raised coastal features. Three major periods of formation were identified :- 1. A pre-glacial or interglacial stage, evidenced by a highlevel rock platform at 32 to 37 m O.D.; 2. Raised beaches and deltas lying between 21 and 28 m O.D. relating to a period of very early Lateglacial deglaciation; 3. Postglacial features lying below about 10 m O.D. Pollen analysis of core sequences from two sites helped confirm the Loch Lomond Readvance age of the end moraines in Strath a' Bhathaich and to elucidate the history of vegetational development in the area between ca. 13,000 and 9,000 B.P. The Lateglacial pollen diagram indicates early development of a treeless Empetrum- dominated landscape that reverted during the Stadial to tundra-like conditions with a floristically-poor, open vegetation. Both Postglacial diagrams indicate a rapid recovery in early Postglacial times, with the return of pioneer species shortly superceded by a closed vegetation, and then by immigration of birch trees, and the establishment of a mixed birch-hazel woodland.

Relative sea level (RSL) reconstructions from paleo records are often the most valuable data set in testing and constraining glacial isostatic adjustment (GIA) models. In some regions, the amplitude and rate of the reconstructed RSL changes are large making the data difficult to fit. Arguably, the reconstructed RSL curve from Maine, USA, is the classic example of such a data set with peak values at about 120 m dropping to a low stand of around -40 m within a few kyr. To our knowledge, no GIA model has captured these extreme variations and the record has been somewhat neglected by the GIA community. Here we critically assess and present a revised pre-10 ka RSL data base for this region and combine it with two recent Holocene compilations. To determine if a successful model fit can be found, output based on a parameter set of five ice models and 440, spherically-symmetric, Maxwell Earth viscosity models was compared to the compiled data. Results show that none of the ice models produce a good fit for the large suite of 1D viscosity models considered. Specifically, the modelled timing and rate of RSL fall are generally too early and low, and the RSL low stand from the models is significantly higher than that observed. A model sensitivity analysis suggests that Earth models that can simulate time-dependent viscosity (e.g., those including transient and/or non-linear effects) are required to fit the Maine RSL data set.

Ice streams are the dominant drainage pathways of contemporary ice sheets and their location and behaviour are viewed as key controls on ice sheet stability. Identifying palaeo-ice streams is of paramount importance if we are to produce accurate reconstructions of former ice sheets and examine their critical role in the oceanclimate system. Many workers have invoked palaeo-ice streams from a variety of former ice sheets, despite a limited understanding of their glacial geomorphology. This thesis addresses the problem by predicting several diagnostic geomorphological criteria indicative of ice stream activity. These are developed objectively from the known characteristics of contemporary ice streams and can be summarised as: large flow-set dimensions (>20 km wide and >150 km long), highly convergent flow patterns, highly attenuated subglacial bedforms (length:width >10: 1), Boothia-type dispersal plumes, abrupt lateral margins «2 km), ice stream marginal moraines, evidence of pervasively deformed till, and submarine sediment accumulations (marine-terminating ice streams only). Collectively, the criteria are used to construct conceptual landsystems of palaeo-ice stream tracks. Using satellite imagery and aerial photography to map glacial geomorphology, identification of the criteria is used to validate the location of a previously hypothesised ice stream and identify a hitherto undetected palaeo-ice stream from the former Laurentide Ice Sheet. Implications for ice stream basal processes are explored and their ice sheet-wide significance is assessed. On Victoria Island (Arctic Canada) five of the geomorphological criteria are identified and the extent of the marine-based M'Clintock Channel Ice Stream is reconstructed at 720 km in length and 140 km in width. The ice stream (operating between 10,400 and 10,000 yr BP) was located within a broad topographic trough, but internal glaciological processes, rather than properties of the bed controlled the margin locations. It eroded into pre-existing unconsolidated sediments and left a spectacular pattern of subglacially-produced landforms, recording a snapshot view of the bed prior to ice stream shut-down. Sediment availability appears critical to its functioning (deformable bed?) and the debris flux of the ice stream is inferred to have been high. Frictional shut-down occurred once down-cutting through sediments reached hard bedrock close to the terminus. The presence of four of the geomorphological criteria are used to identify a terrestrial ice stream which drained the Keewatin Sector of the Laurentide Ice Sheet between ca. 10,000 and 8,500 yr BP. Its size is reconstructed at over 450 km in length and 140 km in width, and it left behind a subglacial bedform pattern consisting of highly attenuated drumlins (length:width ratios up to 48: 1) displaying exceptional parallel conformity. This represents an isochronous bedform pattern and variations in lineament elongation ratio are thought to be a useful proxy for ice velocity. Highest elongation ratios occur immediately downstream of a topographic step where the ice stream entered a sedimentary basin. It is inferred that the ice stream was triggered by climatic warming which altered the ice sheet configuration and the thermal state of the bed. A switch from cold to warm-based conditions probably triggered rapid basal sliding. The ice stream (and a tributary) shut down when it ran out of ice, causing widespread thinning of the ice sheet and subsequent deglaciation. These ice streams denote considerable ice sheet instability over both hard and soft (deformable) beds and emphasise the enormous effects that ice streams had in controlling the deglaciation of the Laurentide Ice Sheet.

The objective of the research reported in this thesis was to elucidate the mode of disappearance of the last ice-sheet to cover the Loch Long/Loch Fyne area in the SW Highlands, and to establish the sequence of raised shorelines that has been formed as a result of the interplay between eustatic and isostatically-induced sea-level changes consequent upon the melting of the ice. The study was geomorphological in orientation and a methodology was adopted that involved mapping, at a scale of 1:10,560, all glacial, fluvial and marine landforms below approx. 75 - 100 m O.D., and the subsequent accurate instrumental surveying of all relevant landforms. A certain amount of mapping back from the coast was also carried out where relevant. The errors inherent in the methods adopted and in the use of various types of marine landforms were quantitatively assessed and it was concluded that raised shorelines could be reconstructed with an accuracy of ±0.54 m using intertidal deltas and ±0.61 m using marine erosional features. The southern part of the study area was deglaciated first at ca. 13,000 yr BP. The dominant mode of deglaciation was that of rapid retreat in the sea lochs (possibly as much as 500 m/yr) due to calving that left isolated dead-ice masses in various side valleys. This retreat was punctuated by two major periods of stillstand or readvance, the Otter Ferry Stage (ca. 12,900 ± 200 yr BP) and the Loch Lomond Readvance (ca. 11,000 - 10,000 yr BP). Eight raised shorelines have been identified as having formed during the relative fall of sea-level from ca. 38 - 40 m O.D. that accompanied the disappearance of the icesheet. A particularly well developed shoreline, CLG2, was formed during the Otter Ferry Stage. A further unique rock-cut shoreline, the Main Rock Platform, was at least in part formed during the cold conditions immediately prior to and during the Loch Lomond Stadial. During the Loch Lomond Stadial glaciers extended down Loch Long to near Ardentinny and down Loch Fyne to beyond Furnace. The mountains in the NE of the study area stood proud of the ice mass as nunataks whilst a number of small valley glaciers occurred in the S of the Cowal Peninsula. Analysis of shoreline gradients and the sea-level change curve suggests that this build-up of ice was sufficient to depress the earth's crust anew. During the early part of the Flandrian Period a major transgression has been recorded by radiocarbon-dated buried peats. This transgression culminated some time after 7,200 yr BP in the formation of a major raised shoreline (CFl) and during the subsequent regression a further five shorelines were formed.

The area of Lycksabäcken northwest of Lycksele is a national interest of natural conservation because of its geological values with many unique landforms. Many of these landforms indicate that the deglaciation process in the area was very complex. However, the deglaciation process in the area has not previously been fully understood. The aim is to add to the knowledge of the events that took place during the last deglaciation. To do this, the glaciofluvial landforms in the area were mapped by studying aerial photographs with a Wild Aviopreter and a five-day field inventory of key areas for the interpretation. These landforms were then transferred to a map in ArcGIS in which scenarios of the deglaciation were constructed. The inversion from landform pattern to a scenario of the deglaciation was based on seven general assumptions and the attempt to create the least complex explanation of the origin of these landforms. The results show that the valley of Umeälven must have been blocked at least three times during the deglaciation in the area, which lead to a redirection of the meltwater flow into the area of Lycksabäcken. There, dead ice played a major role in the formation of the glaciofluvial landforms by damming lakes which enabled delta formation, the formation of many meltwater channels and a large sandur. During the field inventory a large amount of preglacially weathered rock surfaces was found in the area which would be interesting to investigate further.

No description available.

During the late or post Weichselian glacial periods, about 9500 years ago, several faulting associated with large scale earthquakes were triggered in northern Fennoscandia. The end- or post-glacial scarps have a range of the lengths c. 3 to 155 km and the heights 0 to 30 m while most of them are reverse faults trending NE-SW with SE dips. In this literature study, I try to compile the estimated history and cause of seismicity in northern Sweden, and predict the future activity. The result indicates that although the timing of these faulting might not be in the same phase of deglaciation, the upheaval induced by glacial retreating is considered as the major factor of these paleoseismicity. Since the strain from glaciers has been mostly released, the main cause of recent earthquakes in this region is tectonic stress accumulation. Accompanied by the progress of observing techniques such as drilling and grand penetrating radar detection especially in this decade, the geometry of these glacially induced faults and recent micro-seismicity in the vicinity of these scarps have been detected better and better. According to the results, the recorded epicenters form clusters in the east side of the faults’ zone. It implies the correlation between recent seismicity and end- or post-glacial faults. However, there is still insufficient data of the faults’ structure and previous seismicity in order to clarify the faults’ geometry, the age of main movements and estimate their future activity. More investigations are expected to take place in this region.

The purpose of this study was to map the distribution of till-covered eskers in the inland of Västerbotten County in northern Sweden. The top layers of big eskers along the valleys of Öre River, Ume River and Vindel River were investigated through shallow digging. Findings were investigated through field assessment and soil analysis and many locations with till-covered eskers have been identified in Västerbotten's inland in this survey. The till covering the eskers has probably been transported only short distances and has its origins in glacifluvial material. The pattern is not consistent and there are areas where till does not cover the eskers. This can be explained trough irregular till deposition or that the till has been washed away or alternatively that the upper layer that is interpreted as glacifluvial material actually is till that has only been transported for very short distances. The findings of till-covered eskers in Västerbotten means that the traditional view of the eskers originating from the last deglaciation (Weichsel 3) may need to be reviewed. Where overlaying till has been found on top of eskers it means that the eskers must have originated in an earlier glaciation than the last. Only one layer of till could be discerned on the eskers in the survey, so an explanation could be that the till formed during Weichsel 3 and that the eskers formed earlier by the deglaciation of Weichsel 2, but dating the layers in till-covered eskers is difficult. No transition zone between till-covered to not till-covered eskers was found in this study.

I denna studie undersöks hur vattenmiljön förändrades i ett område av västra Yoldiahavet, idag sjön Myssjaren i östra Mellansverige. Syftet med undersökningen har varit att återskapa hur vattnets salthalt förändrades i området genom att studera förekomsten av fossil från saltvattenkrävande bentisk kalkskalsfauna i lera från perioden. Fossil hittades från sju år, 10 395-10 388 lervarvsår BP, av den 31 år långa period, 10 410-10 379 lervarvsår BP, som har undersökts. Utifrån fossilförekomsten kunde det konstateras att vattnet var bräckt under dessa sju år. Eftersom att fossil inte hittades från tidigare och senare perioder Därför är det möjligt att vattnet var bräckt både före och efter denna period. Det som begränsade de undersökta arternas utbredning i området var halten suspenderat sediment i vattnet. Det var en konsekvens av att mycket sediment transporterades till området i och med att området befann sig mellan två större utlopp av glacialt smältvatten. Därför har denna studie, förutom att konstatera att vattnet var bräckt under den undersökta perioden, även visat en succession av arter i Yoldiahavet. I studien identifieras också en 4 år lång kallperiod som varade mellan 10 393-10 389 lervarvsår BP. Vid 10 387 lervarvsår BP börjar iskanten att avancera, troligen som ett resultat av denna kallperiod, vilket slutligen leder till att de undersökta arterna upphör att förekomma i leran.