First Report of a Preserved Weichselian Periglacial Surface in NW Europe—the "P. van der Lijn": Geological Reserve in The Netherlands

Durch Frost gespaltene Steine und Blöcke und durch Windschliff polierte und auf der Oberfläche sortierte Steine in einem vegetationsfreien geologischen Reservat im Zentrum der Niederlande werden beschrieben. Sie werden als Anzeichen für eine weichselzeitliche periglaziale Oberfläche gedeutet. Bisher hat man sie als eine holozäne Abrasionsfläche aufgefaßt.researc

Testing of a low-mobility grout material for permeation grouting in embankment dams

Embankment dams may be damaged by internal erosion, which ultimately may lead to a failure. During internal erosion, finer soil particles from the core soil are being washed out. To restore the core function, injection grouting may be undertaken. Grouting the core of an embankment dam should be performed with a grout with similar characteristics as the original core soil. This grout type is commonly used in compaction grouting, e.g., a low mobility grout. The grout is similar to a fine-grained moraine core soil, but given its stiffness, it is difficult to permeate a damaged core soil. A modified low mobility grout containing sand, limestone filler, bentonite, plasticizer, air release agent and water has been tested in the laboratory with focus on permeation. Grouting was done in different sized aggregates. Impact of paste-to-aggregate ratio, grout consistency, maximum grain size of grout, coarseness of grouted material, and grouting methodology was tested. Higher paste-to aggregate ratios and lower viscosity/yield strength in/of the grout improved the permeation. Initially pressurized grouting compared to only hydrostatic pressures followed by stepwise pressure increased grouting was furthermore identified as a factor to improve the permeation. Funder: Svenskt Vattenkraftcentrum (SVC)</p

The first independent chronology for Middle and Late Weichselian sediments from southern Sweden and the Island of Bornholm

Conventional Optically Stimulated Luminescence (OSL) dating using the equivalent dose distributions of 8 mm aliquots have been extended to key stratigraphical sites in southernmost Sweden and the island of Bornholm. The objective has been to bridge the lack of an independent chronology, which might catalyze a new understanding of the ice flow patterns related to the initiation of the Last Glacial Maximum, and the stratigraphical development during the deglaciation sequence. Sediments from proximal environments are usually 10-15 kyr older than expected from regional stratigraphical correlations and radiocarbon dates of mammoth tusks. We propose that OSL signals are inherited from reworked sediments that were sufficiently bleached prior to glacial or glaciofluvial transportation and deposition. Sediments from distal and beach environments seem to indicate proper depositional ages. Thus, the main Weichselian stadial was preceded by almost 20 kyr of ice free conditions, succeeded by an ice advance from south-southeast before northeasterly ice flow predominated. Major inconsistencies still exists for the final deglaciation. Two distinct environmental reconstructions of the uppermost diamict at two separate sites, both superimposed on a periglacial surface, predict either deposition during subaquatic conditions associated with drifting icebergs after 16 kyr or subglacial sedimentation associated with an ice advance in Oresund. It remains unsolved whether the periglacial surface at the two sites can be correlated or if they represent two different stratigraphical levels. In perspective, the introduction of OSL dates in Skane has identified the periglacial marker horizon or horizons as targets for future intensive dating

Glacial history and shoreline displacement on Erdmannflya and Bohemanflya, Spitsbergen, Svalbard

Traces of former glaciation were studied on Erdmannflya and Bohemanflya. Both peninsulas were probably completely covered by glaciers during the Late Weichselian and the final dcglaciation took place around years BP. Esmarkbreen readvanced shortly after 9,500 BP, probably a local and shortlasting event. Raised beaches occur to about 60 m above sea level, and date back to about 10,000 BP. Initial land emergence was rapid, about 3m/100 years. It seems to have been followed by a marine transgression between 8,500 and 7,500 BP, which resulted in a large and distinct beach bridge and marine abrasion cliffs about 10-12 m above present sea level. Mytilus edulis lived in the area between at least 9.000 and 5,000 BP. Five thousand years ago relative sea level probably stood 3-4 m higher than today. Relative sea level has remained close to present during the last centuries. Different positions of glacier fronts in this century have also been mapped