Adrian M. Hall

When large volumes of meltwater arrive suddenly at the glacier bed, the capacity of subglacial conduits is exceeded, generating transiently high fluid pressures. Yet we currently lack reliable markers for where such conditions developed on the beds of former glaciers. Here, we describe hydraulic damage that developed at close to or above overpressu...

Inheritance from prior exposure often complicates the interpretation of terrestrial cosmogenic nuclide (TCN) inventories in glaciated terrain. Lochnagar, a mountain in eastern Scotland, holds a clear geomorphological record of corrie glaciation and the thinning of the last Scottish ice sheet over the last ~15 ka. Yet attempts to date the main stage...

Understanding processes that operate beneath rapidly melting ice margins is critical for predicting the responses of the ice sheets to anthropogenic global warming. Where large or rapid meltwater inputs arrive at the ice sheet bed, ice flow may temporarily accelerate, and meltwater flow mobilises and erodes sediment. Where the capacity of subglacia...

ISSN 1404-0344 This report presents results for a set of Terrestrial Cosmogenic Nuclide (TCN) samples taken from four sites close to the present shoreline at Forsmark. The sampling was undertaken to support a new study of glacial micro-forms and erosion rates during deglaciation. The samples extend the previously reported TCN dataset for the wider...

Glacial erosion in the Öregrund archipelago has led to the formation of rock trenches, valleys and basins, now submerged between the low-lying islands. The depths of these topographic depressions are 10–50 m, greater than in areas to the West and South. This study explores the likely reasons for enhanced glacial erosion in the Öregrund archipelago...

Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet — the third largest Quaternary ice mass that spanned 49°N...

Ice sheet interiors are conventionally regarded as non‐erosive. Yet subglacial conditions may be transformed during deglaciation by the arrival of large volumes of meltwater at the ice sheet bed. The development of a dynamic meltwater drainage system and the onset of basal sliding have potential to increase erosion rates in bedrock and sediment. He...

Glacial ripping involves glaciotectonic disintegration of rock hills and extensive removal of rock at the ice-sheet bed, triggered by hydraulic jacking caused by fluctuating water pressures. Evidence from eastern Sweden shows that glacial ripping caused significant subglacial erosion during the final deglaciation of the Fennoscandian ice sheet, dis...

The cosmic-ray muography is an emerging imaging technique that exploits the attenuation of the penetrative muons originating from the interactions between high-energy cosmic radiation and the atmosphere. We propose that the differential attenuation of muons in laterites, saprolites, bauxites and fresh rocks can be muographically employed in the stu...

Fracture caves in Sweden are important for understanding the processes which operated under the last ice sheet as it melted. The distribution of fracture caves, disinte�grated rock hills and boulder spreads help us to reconstruct where glacial meltwater reached overpressure beneath the ice. That provides a new window on subglacial hydrology. The br...

Hundreds of caves have been located and explored by generations of cavers in lowland Sweden. Often the caves sit within fields of huge, rotated and moved blocks where the rock has the appearance of having been burst or blasted apart. These are quite unlike the limestone solution caves found in many parts of the world because, unusually, many Swedis...

Cosmic-ray muography is a novel methodology for monitoring and spatial imaging density variations in solid and liquid materials. The capabilities of muography are particularly fitting for studying bedrock fractures, weathering and the inner structure of different landforms. Detectors must be positioned behind the open sky (the source of muons) and...

Roches moutonnées are typical landforms of glacial erosion developed in hard rocks, with an asymmetric profile caused by abrasion and lee-side plucking. In eastern Sweden, some roches moutonnées show extensive damage, including open fractures, disintegration into blocks, fracture caves and short boulder trains. Disintegration increases along ice-fl...

Bauxites are mature laterites develop under a long period of extreme chemical weathering in a humid, tropical to subtropical climate. Bauxites are, in fact, among the best climate-sensitive rock indicators for warm and humid paleoclimates. They also represent a useful proxy for past climate changes and are important for provenance studies and geody...

The Shetland Isles display a remarkable diversity of geology and landforms. The varied relief and topography and the indented coastline are strongly influenced by the bedrock geology and structure at a variety of scales. During the last glaciation, Shetland supported an independent ice cap that extended across the adjacent continental shelves. Land...

The landscapes and landforms of Orkney and Caithness have been profoundly influenced by the varied lithology and structures of the Devonian sedimentary cover. During the Neogene, an extensive planation surface developed across Caithness, with sandy weathering covers, which was subsequently uplifted and dislocated by fault movements. In the Pleistoc...

The Outer Hebrides Platform extends west from the present island chain towards the Atlantic continental shelf edge and represents a fragment of Archaean crust (Lewisian gneiss) that was differentially uplifted during the Palaeogene and tilted westwards during the Neogene. An extensive planation surface developed close to sea level in the Pliocene a...

Buchan displays some of the clearest evidence for long-term regional geomorphological development in Scotland. The metamorphic and igneous basement was first exposed in the Devonian and repeatedly buried and re-exposed later in the Palaeozoic and Mesozoic. Greensand, chert and flint remnants attest to a former Cretaceous sedimentary cover. The high...

The Quaternary Period in Scotland was characterized by major climatic shifts and the alternation of glacial and temperate conditions over a wide range of timescales. The extent of multiple glaciations prior to the Mid-Pleistocene Transition (1.25–0.70 Ma) is uncertain, but thereafter up to ten major episodes of ice-sheet expansion occurred. Glacial...

Long-term geomorphology has received little recent attention in Scotland. Palaeosurfaces and major landforms, including valleys and basins, can be linked to the sub-Caledonian and sub-Permian basement unconformities. The present topography was sculpted from the sub-Palaeocene unconformity after kilometre-scale uplift in response to Early Palaeogene...

Dense networks of dilated fractures occur locally in the upper 5–15 m of bedrock in basement gneisses in eastern Sweden. Near Forsmark, pre-existing sub-horizontal fractures have been jacked open and filled with water-lain sediment, likely during the latest Weichselian glaciation. Despite extensive previous research, it is uncertain whether subglac...

Glacial ripping is a newly recognized process sequence in which subglacial erosion is triggered by groundwater overpressure. Investigations in gneiss terrain in lowland Sweden indicate that ripping involves three stages of (i) hydraulic jacking, (ii) rock disruption under subglacial traction, and (iii) glacial transport of rock blocks. Evidence for...

Glacial ripping is a newly recognized process sequence in which subglacial erosion is triggered by groundwater overpressure. Investigations in gneiss terrain in lowland Sweden indicate that ripping involves three stages of (i) hydraulic jacking, (ii) rock disruption under subglacial traction and (iii) glacial transport of rock blocks. Evidence for...

Subsurface fracturing and weathering in bedrock are typically studied and imaged with conventional remote geophysical techniques. We introduce a new technique, muography, for carrying out such studies. This technique is based on the detection of atmospheric cosmic-ray induced muon particles after they pass through rock.

Meteorite impact structures can provide important information on long-term denudation on the Earth's cratons. Impact structures in the Fennoscandian Shield contain rocks (i.e., impactites), that have developed during the collision, and, possibly, remnants of the pre-impact sedimentary rocks. The crater depressions may also be filled with post-impac...

The Earth’s cratons are traditionally regarded as tectonically stable cores that were episodically buried by thin sedimentary covers. Cratonic crust in southern Finland holds seven post-1.7 Ga tiered unconformities, with remnants of former sedimentary covers. We use the geometries of the tiered unconformities, along with previously dated impact str...

Plain Language Summary The “critical zone”—the life‐sustaining part of the Earth that extends from the top of the tree canopy to the bottom of permeable bedrock—is essential for ecosystems and agriculture. The opening of bedrock fractures and onset of water‐rock interaction are crucial to the formation of the critical zone. Within the bedrock, the...

This paper reviews the distribution, character and age of blue-ice moraines in Antarctica and asks whether there are implications for the study of former Pleistocene ice sheets in the Northern Hemisphere. Blue-ice forms where acceleration of downslope katabatic winds removes snow and causes ice to ablate. Upward ice flow compensates for the surface...

The present marine Baltic Sea basin (BSB) occupies an eroded Proterozoic intra-cratonic basin on the Fennoscandian shield. Competing models propose a Neogene fluvial origin, with later modification by glacial erosion, or a much younger development, with overdeepening beneath the Fennoscandian Ice Sheet (FIS). We test these alternatives using a firs...

In low relief Precambrian gneiss terrain in eastern Sweden, abraded bedrock surfaces were ripped apart by the Fennoscandian Ice Sheet. The resultant boulder spreads are covers of large, angular boulders, many with glacial transport distances of 1–100 m. Boulder spreads occur alongside partly disintegrated roches moutonnées and associated fracture c...

A 541 million year old unconformity is found widely in Västergötland. The unconformity is developed in gneiss and it is nearly flat. The unconformity was uncovered in the last 1 Ma by removal of overlying Cambrian sandstones by the Fennoscandian ice sheet. The presence of such a starter surface for glacial erosion is unusual and opportune. The sub-...

This report presents results from a detailed study of the past and potential future impact of glacial erosion at Forsmark, Sweden. The work was commissioned by SKB, the Swedish Nuclear Fuel and Waste Management Company. The methods included use of the sub-Cambrian unconformity as a reference surface for glacial erosion, geomorphological mapping and...

Lithostratigraphical studies coupled with the development of new dating methods has led to significant progress in understanding the Late Pleistocene terrestrial record in Scotland. Systematic analysis and re-evaluation of key localities have provided new insights into the complexity of the event stratigraphy in some regions and the timing of Late...

Concentrations of boulders are a common feature of landscapes modified by former mid-latitude ice sheets. In many cases, the origin of the boulders can be traced in the up-ice direction to a cliff only tens to hundreds of metres distant. The implication is that a pulse of plucking and short boulder transport occurred beneath thin ice at the end of...

This paper reviews the changing environments, developing landforms and terrestrial stratigraphy during the Early and Middle Pleistocene stages in Scotland. Cold stages after 2.7 Ma brought mountain ice caps and lowland permafrost, but larger ice sheets were short-lived. The late Early and Middle Pleistocene sedimentary record found offshore indicat...

This paper summarises developments in understanding sea level change during the Quaternary in Scotland since the publication of the Quaternary of Scotland Geological Conservation Review volume in 1993. We present a review of progress in methodology, particularly in the study of sediments in isolation basins and estuaries as well as in techniques in...

The Eurasian ice sheet complex (EISC) was the third largest ice mass during the Last Glacial Maximum with a span of over 4500 km and responsible for around 20 m of eustatic sea-level lowering. Whilst recent terrestrial and marine empirical insights have improved understanding of the chronology, pattern and rates of retreat of this vast ice sheet, a...

Valleys are remarkably persistent features in many different tectonic settings, but the reasons for this persistence are rarely explored. Here, we examine the structural controls on valleys in the Cairngorms Mountains, Scotland, part of the passive margin of the eastern North Atlantic. We consider valleys at three scales: straths, glens and headwat...

Towards the end of the last glaciation, ice sourced from the western Grampian Mountains of Scotland flowed down Strath Spey to encroach on the northern flanks of the Cairngorm Mountains. The maximum of this late advance and its subsequent retreat is recorded by moraines, ice-marginal meltwater channels, and kame terraces that can be traced for 60km...

Three separate till units are recognized on Orkney deposited during the last ice sheet glaciation: the Digger, Scara Taing and Quendal Till members. The Digger Till records an ice advance from the south that extended on to the Atlantic shelf. The Scara Taing Till records a later period of full ice cover when ice moved from the SE out of the Moray F...

This paper reviews existing information on the last glaciation of Caithness and presents new evidence for additional till units and for long distance ice-flow paths based on till palynomorphs, indicator erratics and striae. Early, radial expansion of Northern Highland ice probably occurred at 31 – 29 ka. After ice withdrawal from the north coast, M...

We present a review of over 175 years of research into the Middle to Late Devensian (Weichselian) glaciation of NE Scotland based crucially on both its lithostratigraphic and geomorphic records. The location of the region, and surrounding seabed, makes this unusually detailed record significant for deciphering the former interactions and dynamics o...

The Peloponnese in southwestern Greece fronts the Hellenic Arc at the boundary between the European and African plates. The relief is developed across deeply eroded nappes and folds that represent the roots of Alpine mountains developed during Early Miocene collision. During the Plio-Pleistocene, the geomorphological develop- ment of the region was...

The nature of the regolith that existed on the shields of the Northern Hemisphere at the onset of ice sheet glaciation is poorly constrained. In this paper, we provide the first detailed account of an exceptionally preserved, deeply weathered late Neogene landscape in the ice sheet divide zone in northern Finland. We mine data sets of drilling and...

Contrasting views exist on the stability of the Earth’s shield regions over the last 1 Ga that have major implications for reconstructing erosion patterns on shields and the supply of sediment to intra-cratonic and marginal basins. This paper explores Phanerozoic denudation rates and patterns on the northern part of the Fennoscandian Shield in the...

Europe’s largest Fe oxide deposits are hosted in Palaeoproterozoic supracrustal rock of the Fennoscandian Shield in the northern Norrbotten province, Sweden. Significant clay alteration zones occur at the present land surface and at depth in the Kiirunavaara, Malmberget, Gruvberget, Leveäniemi and Mertainen iron oxide-apatite deposits that are host...

Glacial cirques and the relationship between equilibrium line altitudes and mountain range height Ian S Evans, Adrian M Hall, and Johan Kleman Cirque-driven lowering is not a global control on mountain summit heights. The glacial ‘buzzsaw’, considered to operate at past and present ELAs, cannot apply where summit plateaus above cirques have not bee...

Stable isotope ratios can provide important evidence for estimating groundwater temperatures during the formation of clay minerals in response to chemical weathering of rocks at the landsurface. In this paper, we investigate weathering kaolins found in Buchan, NE Scotland. Stable oxygen and hydrogen isotopes for kaolins from weathered clasts in pos...

The position of Fair Isle on the Atlantic-North Sea divide makes it a critical location for understanding the dynamic flow patterns of the last and perhaps earlier ice sheets in Northernmost Scotland and the adjacent offshore areas. Fair Isle may have been crossed by ice from three main sources around the Northern North Sea: the Shetland mainland,...

The question of whether the Shetland Islands were covered by an ice cap or by an ice sheet during the last glacial cycle (40–10 ka) remains unresolved. This paper addresses this problem using existing and new data on glacial erratic carry, striae, glacial lineaments and roche moutonnée asymmetry. Its focus is on eastern Shetland, where ice-cap and...

The buzzsaw hypothesis refers to the potential for glacial and periglacial processes to rapidly denude mountains at and above glacier Equilibrium Line Altitudes (ELAs), irrespective of uplift rates, rock type or pre-existing topography. Here the appropriateness of the buzzsaw metaphor is examined alongside questions of the links between glacial ero...

Glaciated passive margins display dramatic fjord coasts, but also commonly retain plateau fragments inland. It has been proposed recently that such elevated, low-relief surfaces on the Norwegian margin are products of highly efficient and extensive glacial and periglacial erosion (the glacial buzzsaw) operating at equilibrium line altitudes (ELAs)....

Allochthonous Cenozoic microfossils have been reported from Late Pleistocene lake and mire host sediments across an area of > 30,000 km2 in northern Finland. Two main groups of microfossils are recognised: Palaeogene marine diatoms, silicoflagellates and ebridians that include taxa from around the time of the Palaeocene-Eocene Thermal Maximum and P...

We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlinin...

a b s t r a c t We examine 10 Be concentration in two pit profiles in the Parkajoki area at w67 N on the northern Fennoscandian shield in northern Sweden. Due to repeated cover by cold-based, non-erosive ice sheets, the area retains many relict non-glacial features, including tors and saprolites. In the examined pit profiles, gruss-type saprolite d...

The erosional effect of ice sheets on shield bedrock surfaces has been debated for many decades. Whilst there seems to be agreement that ice sheet erosion of the bedrock landforms was generally modest, and that many preglacial landscape elements remain, we need to know which factors influence ice sheet dynamics and erosional impact on the shield. U...

We investigate the long-term geomorphological evolution of the inselberg plains on the glaciated northern Fennoscandian shield. The shield surfacehas been largely stripped of pre-Quaternary correlative sediments and saprolites by non-glacial and glacial erosion, which make investigations of pre-Quaternary landscape development a challenge. The reli...

The long-term geomorphic evolution of shield surfaces is poorly understood, especially of glaciated shields where saprolites and correlative sediments have been removed by glacial erosion. We know the rough picture of land uplift and erosional unloading during the Cenozoic (e.g. Hendriks et al., 2007) and we know of the existence of stepped surface...

A confluence zone existed within the northern sector of the last British Ice Sheet (BIS) where ice flowing from the Northern Highlands met ice streaming out of the Moray Firth and across the plain of Caithness. At Wester Clett, a complex 35m thick sequence of glacigenic sediments provides important evidence of dynamic interactions between these ice...