Pre-glacial Channel Research Articles

Characterisation of gravel deposits in the pre-glacial channel, Central Dublin

Characterisation of gravel deposits in the pre-glacial channel, Central Dublin

Characterisation of gravel deposits in the pre-glacial channel, Central Dublin

Characterisation of gravel deposits in the pre-glacial channel, Central Dublin

Paleofluvial and subglacial channel networks beneath Humboldt Glacier, Greenland

The identification of subglacial drainage systems can inform our understanding of past and present hydrological processes, landscape evolution, and ice dynamics. Here, we present evidence from satellite imagery, digital elevation models, and radio-echo sounding data for a series of channelized networks with contrasting paleofluvial and subglacial origins beneath Humboldt Glacier, northern Greenland. A >250-km-long, dendritic paleofluvial channel network beneath the northern portion of Humboldt is interpreted as a preglacial feature. Roughly linear channels beneath the southern portion of Humboldt, which display a similar distribution to tunnel valleys found on the beds of former ice sheets, are likely to have been eroded by subglacial meltwater routed along the ice-sheet bed. We suggest that basal meltwater is actively being routed down both the paleofluvial and subglacially formed channel networks to the coast. Inheritance of the preglacial channel network may have influenced the present-day location and dynamics of Humboldt Glacier and enhanced selective erosion at its down-glacier end.

The Buried Pre-Glacial Channel at Newcastle, Co. South Dublin

The Buried Pre-Glacial Channel at Newcastle, Co. South Dublin

The Buried Pre-Glacial Channel at Newcastle, Co. South Dublin

The Buried Pre-Glacial Channel at Newcastle, Co. South Dublin

Pre-glacial topography of the European Alps

Research Article| December 01, 2012 Pre-glacial topography of the European Alps Pietro Sternai; Pietro Sternai * Swiss Federal Institute of Technology (ETH), Zürich, Switzerland *E-mail: pietro.sternai@erdw.ethz.ch. Search for other works by this author on: GSW Google Scholar Frédéric Herman; Frédéric Herman Swiss Federal Institute of Technology (ETH), Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Jean-Daniel Champagnac; Jean-Daniel Champagnac Swiss Federal Institute of Technology (ETH), Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Matthew Fox; Matthew Fox Swiss Federal Institute of Technology (ETH), Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Bernhard Salcher; Bernhard Salcher Swiss Federal Institute of Technology (ETH), Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Sean D. Willett Sean D. Willett Swiss Federal Institute of Technology (ETH), Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Geology (2012) 40 (12): 1067–1070. https://doi.org/10.1130/G33540.1 Article history received: 17 Apr 2012 rev-recd: 07 Jun 2012 accepted: 13 Jun 2012 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Pietro Sternai, Frédéric Herman, Jean-Daniel Champagnac, Matthew Fox, Bernhard Salcher, Sean D. Willett; Pre-glacial topography of the European Alps. Geology 2012;; 40 (12): 1067–1070. doi: https://doi.org/10.1130/G33540.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We present a topographic reconstruction of the European Alps prior to Quaternary glaciation, based on the assumption that this topography was a steady-state fluvial landscape eroding according to a stream-power law, but with spatially variable channel steepness. We find high pre-glacial channel steepness in the western Alps and on the harder rocks of the basement and metamorphic nappes, while lower values are often associated with weaker Alpine flysch deposits. The reconstructed pre-glacial river network also provides an estimate of distribution and magnitude of glacial erosion and associated isostatic adjustment, suggesting an increase of valley-scale topographic relief and decrease of mean elevation throughout glaciation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Retaining wall behaviour in Dublin's fluvio-glacial gravel, Ireland

Practising engineers in the Dublin, Ireland, area have significant experience in dealing with the Boulder Clay which underlies much of the city. However, the 45 m deep buried pre-glacial channel north of the River Liffey is infilled with fluvio-glacial deposits which behave very differently from an engineering point of view. Case history data from eight sites and a detailed examination of the retaining wall behaviour at two of the sites show that retaining wall movements appear to be governed by system stiffness (i.e. a combination of wall stiffness and support configuration). It seems that relatively simple beam–spring type computer programs will provide data for reasonably accurate designs of retaining walls for basements of up to two levels. Input parameters such as K0, φ‘ and soil stiffness need to be carefully specified. Groundwater inflows can be significant but can be dealt with by providing a good cut-off into the underlying glacial till or bedrock and by conventional pumping techniques. Geophysical techniques such as multichannel analysis of surface waves, S/P waves and resistivity can be very useful for the determination of soil properties, such as degree of saturation, density and stiffness, and for material characterisation (i.e. distinguishing the presence of these materials in contrast to the Boulder Clay).

Insect faunas associated with palaeolithic industries from five sites of pre-Anglian age in central England

Fossil insect faunas are described from five sites where organic silts fill ancient river channels. Two of the sites (Waverley Wood and Brooksby) are in the English Midlands and the other three of them (High Lodge, Happisburgh and Pakefield) are in East Anglia. Their stratigraphical contexts can be shown to pre-date the Anglian (Elsterian) Glaciation. All these localities are associated with palaeolithic implements. Three of them, Waverley Wood, Brooksby and High Lodge, are riverine deposits related to the pre-glacial Bytham River valley. The channel at Happisburgh probably dates from the same period though it was probably not part of the main Bytham River valley. The insect fauna from the pre-glacial channel at Pakefield suggests that it is not of the same age as the others. The insect assemblages include exotic species that enable stratigraphical correlations to be made with other sites in central England. They provide detailed information on the local environment and regional climate at the time when palaeolithic peoples were living in central England.

The 1939 Montagneuse River landslide, Alberta

The 1939 landslide on the west wall of the Montagneuse River valley, 1300 m long, 1400 m wide, and 80 m thick with av olume of 76 ×10 6 m 3 , is the largest historic rapid landslide on the Interior Plains of Canada. It lasted about a minute, dammed the river, and formed a reservoir 1.5 km long. The reservoir was filled before 1952 by lake deposits, which were eroded by the river by 1988. The landslide contained two major blocks. The downslope block, 950 m long, kept intact without obvious tilting, indicating that the block moved almost horizontally on a comparatively deep rupture surface. The displaced material included part of the preslide river channel so the Montagneuse River was pushed eastward. The toe of the block moved up and dammed the river. The upslope block, with a length of 300-350 m, slid with little rotation but broke up into at least five smaller blocks. Most trees on the upslope block postdate the slide. Two sag ponds on the landslide, visible in 1952, had enlarged by 1988, probably a result of water running off from the recently cleared farmland behind the scarp. The main scarp has been substantially modified by earth flows and slides. Landslides in the Montagneuse River valley coincide with the Shaftesbury buried preglacial channel of the Peace River. The surfaces of rupture of five historic landslides in the Peace River Lowland follow clays deposited in preglacial channels, confirming that these deposits may be hazardous when eroded.

Factors affecting distribution of landslides along rivers in southern Alberta

A regional study of the distribution and characteristics of landslides along four major rivers in southern Alberta was undertaken in order to relate landslide activity to geologic and physiographic factors such as bedrock outcrop, groundwater, river sinuosity, and the aspect of valley slope. This provides greater insight into the factors controlling slides in the study region, particularly in the Cretaceous bedrock.The study was based on an analysis of air photos, augmented by surficial and bedrock geologic maps and hydrogeologic and bedrock topographic maps. The area is underlain by a thick sequence of gently dipping sedimentary strata of Upper Cretaceous age. Late Pleistocene glaciation deranged the drainage to some extent and the rivers studied now occupy postglacial channels in some reaches and are re-excavating preglacial channels in other reaches.The results of the study indicate that the bedrock type is of considerable importance since there is marked difference in valley wall stability between relatively unstable marine formations and the relatively stable nonmarine formations. Areas of comparatively high groundwater exert an obvious influence on landsliding. The importance of buried valleys in locally drawing down the water table is clearly evident. More than 90% of the landslides occur in meander bends and are related to river erosion.Failures in the bedrock appear to be translational whereas those higher on the valley wall in Pleistocene sediments are largely rotational. The data have been assembled on a profile of the river and present a regional picture of landslide activity over a large area.

NEW YORK BAY—BEDROCK PROFILE

Completion of a series of test-borings across New York Bay yields information bearing on the depth of bedrock of the pre-Glacial channel of the Hudson River. The absence of a deep bedrock gorge is indicated by the evidence of the borings.

Buried preglacial ground water channels in the Albany-Schenectady area in New York

A map is presented showing contours of the buried preglacial channel of the Mohawk River from Schenectady, New York, to its confluence with the Hudson River about 12 miles south of Albany and of associated buried preglacial channels. The Pleistocene history of a portion of the Mohawk and Hudson Rivers is discussed, and the relation of buried valleys to ground-water supplies is indicated.

More Evidence That Platte River, Nebraska, Formerly Connected with Grand River, Missouri

As it is uncertain whether this investigation may be carried further very soon, it seems well to place on record a report of progress to date. In preparing a paper on the Pleistocene history of the Missouri river (Science, n. s., vol. xxxix, p. 263 et seq.), in examining the topography of the country it was found that the steepest slope from a point near Nebraska City on the Missouri river was not along the course of the Missouri, but southeast to the vicinity of Stanberry, on Grand river, Missouri. Attention was called to the fact, and the theory was proposed that preceding the Kansan stage of the great glacier the drainage was southeastward rather than along the line of the present Missouri. Another fact was recalled that in the preparation of Bulletin 158 of the United States Geological Survey, reference had been made to the report of the United States engineers for 1890, which stated that a deep preglacial channel had been discovered near Nebraska City. As no other similar case was found at the time of publication of said Bulletin 158, it was judged more probable that some Pennsylvanian strata had been mistaken for till and glacial gravels. With a map of the region in hand, it will be noticed that there is a branch of the Grand river rising near Platte river, Missouri, and flowing southeast. 179

A Striated Surface at Sandsend

Though glacial beds cover the solid rocks of the Yorkshire coast from Redcar to Bridlington, glaciated surfaces are rare. This arises from the texture and comparatively soft nature of the Jurassic and Cretaceous strata, of which East Yorkshire is built. Hard bands do, however, occur here and there in the Oolitic beds, and in two localities, Filey and Robin Hood’s Bay, striated surfaces have been observed upon them. The object of the following note is to record an additional locality. Sandsend is a small fishing village, picturesquely situated on the Yorkshire coast, two and a half miles north of Whitby, at the point where the Sandsend beck enters the sea. South of the beck, the high cliffs overlooking the sea are for the most part composed of boulder clay and gravel, and there is evidence that in the neighbourhood of Upgang the drifts fill in a pre-glacial valley, believed by Mr. G. Barrow to be the pre-glacial channel of the Esk. North of the beck the high ground consists of Jurassic rocks covered by drift. These beds are well exposed on the coast, and can also be seen in the series of old quarries connected with the abandoned Sandsend alum works. Throughout these old workings the “ Dogger” Oolite (a very variable bed) overlies the alum shale, and is represented by a conspicuous band of evenly-bedded, hard, ferruginous sandstone, thirty feet thick, flaggy towards the bottom, but massive and exceedingly hard at the top. The boulder clay which overlies the ...

The preglacial channel of Eagle River, Keweenaw Point, Lake Superior

The preglacial channel of Eagle River, Keweenaw Point, Lake Superior