Till Beds Research Articles

The Flow of Ice Over a Till Bed

AbstractThis paper considers the contribution made to overall glacier flow by deformation of an unlithified bed. The flow pattern in deforming till beneath a glacier is determined for the case of a uniform ice slab resting on a uniform thick till bed. The results obtained show that, once the till is saturated, very little surplus water is needed to produce high velocities in the till near the ice−till interface, the interface velocity varying as the 5/2 power of the surplus water concentration. This sensitivity to water content suggests that this may be a mechanism inducing glacier surging.

The Flow of Ice Over a Till Bed

Abstract This paper considers the contribution made to overall glacier flow by deformation of an unlithified bed. The flow pattern in deforming till beneath a glacier is determined for the case of a uniform ice slab resting on a uniform thick till bed. The results obtained show that, once the till is saturated, very little surplus water is needed to produce high velocities in the till near the ice−till interface, the interface velocity varying as the 5/2 power of the surplus water concentration. This sensitivity to water content suggests that this may be a mechanism inducing glacier surging.

Till studies and neotectonics in northwest Skiine, south Sweden

A mosaic distribution of Pre‐Quatcrnary rocks in Skåne constitutes good conditions for using gravel analysis in till‐stratigraphical work. Recently discovered neotcctonic movements and their effect on the composition, distribution, and correlation of tills are discussed. With examples from the Kullen arm, it is shown that compositional variability in a till bed, as cvidenl from gt‐avel analysis, can be deciphered and is of great stratigraphical value.

The stratigraphy and genesis of the Dösebacka and Ellesbo drumlins. A contribution to the knowledge of the Weichselglacial history in western Sweden

Abstract The Weichsel-glaciation is represented by a very complicated stratigraphy in the Dosebacka and Ellesbo drumlins, situated on the western slope of the Gota River Valley. It can be subdivided into six cold-warm stages, which are represented by on one hand till beds and glaciofluvial beds, on the other hand interstadial clay and sand layers and first of all deflation surfaces. The older interstadial is called the Older Dosebacka-Ellesbo-interstadial and it is correlated with the Brorup interstadial in Denmark. A mammoth tusk from Dosebacka has been C14-dated at 36 000 B.P. which however is a minimum age since shellac used for preservation purposes may not have been extracted completely. The younger interstadial is called the Younger Dosebacka-Ellesbo-interstadial and it is correlated with the Hengelo-Denekamp-interstadials in Holland. Organic matter from sand layers at Ellesbo, and clay lamina at Dosebacka, have been C14-dated at 30 300 and 24 020 B.P., respectively. The inland ice during the Weichs...

Microfossils in the Quaternary Layers at Tofthög, Southern Scania

Abstract The biostratigraphic study of Tofthog core is the first preliminary part of a more extensive litho- and biostratigraphic survey of the Quaternary layers in the Alnarp Valley. The material was analyzed for its content of pollen, spores, diatoms, silicoflagellates and other microfossils occurring in the pollen and diatom slides. The Tofthog core contains no organic sediments. All the microfossils noted are either reworked or allochthonous. The frequencies of pre-Quaternary (extinct) and Quaternary (extant) pollen show a distinct variation in different strata. According to Andersen (1965), the till with high content of Quaternary pollen is transported from the south or southeast and the tills with dominance of pre-Quaternary material from the north. The various pollen contents in the different till beds at Tofthog show that the lowest till has been transported from N and the middle till from S—SE. The upper till bed can be divided biostratigraphically into a lower part, transported from N and an upp...

Some Aspects on Till Stratigraphy in the Light of Lithostratigraphic Studies on the Kullen Peninsula in Northwestern Scania

Abstract In the Kullen region in northwestern Scania, the author has examined the lithologic composition of the fine gravel fraction in different till beds, with the aim of elucidating the direction and chronology of the corresponding ice streams. The determining factor has been to find, in one and the same section, direction-indicating additional material in a till in relation to the immediate older till. Complete till cuttings have been prerequisite for this. Two examples are given of the applicability of the method in the Kullen region, where there are very few conventional indicator boulders. The examples are illustrated by diagrams which show the changes in the lithologic composition of the different stratigraphic levels in each section. The method and results of the author differ in essential respects from those of earlier investigators in this region.

The Quaternary Deposits at Tofthög, Southern Scania

Abstract An investigative exploratory boring through the Quaternary deposits was made at Tofthog in southern Scania in 1964. The thickness of the soil-cover is 110.2 m. The underlying Cretaceous limestone was reached 95 m below sea-level. Most of the penetrated strata were taken up as cores with a diameter of 100 mm. By studying carbonate content, rock-fragment distribution, etc., it has been possible to establish a detailed section through the Quaternary deposits. Among other things, three different till beds were found, the lowest one unique in the area and therefore considered to be of high age.

Glaciation in Southern Argentina More than Two Million Years Ago

In southern Argentina till beds interbedded with lava flows were deposited by ice that extended at least 40 kilometers east of the present crest of the cordillera. The flow covering the oldest till bed is 3.2 +/- 1 million years old. The flow that constitutes the present surface and covers the youngest till bed, is 1.7 +/- 0.5 million years old.

Linear sole markings in Pleistocene till

SUMMARYCurrent-produced sole markings are not uncommon in the Pleistocene continental till deposits of Alberta, Canada. Groove, striation and prod moulds have all been recognized, characteristically occurring in close association on the undersurface of the till beds. These sedimentary structures provide a rapid means by which local ice-flow directions may be determined.

En kolförande morön i Falköping

Abstract A coal-bearing till in Falköping In the city of Falköping in South-Western Sweden an excavation has been made in which are seen three different till beds (b, c, c in Fig. 1) and between two of them a deposit of sand (d). The till b is composed of Palaeozoie limestone and alum shale, the others of limestone only. In the till e there are found boulders and fragments of coal with a vanadium content of 0.4%. These are supposed to originate from the region between Falköping and Torbjörntorp about 6 kilometers NE of Falköping. However, there is perhaps a slight possibility that they may have come from Billingen about 30 kilometers farther to the north, transported by the ice without being entirely crushed.

On the Occurrence of Marine Shells in the Stratified Beds below the Till

I n the basin of the Clyde, the Till or unstratified boulder clay generally rests upon the beds of the coal formation, or upon rocks of an earlier date; and these subjacent rocks are almost always fractured where they are in contact with the Till. There are however exceptions; sometimes the Till rests upon scratched but unbroken surfaces of those rocks; and sometimes, but very rarely, we find immediately below the Till beds of sand, gravel, and laminated clay,—fragments apparently of an older alluvial covering, which has not been entirely removed by the cause, whatever it was, which lodged the Till on the surface. Until the discovery which I am about to communicate, no marine remains had been found in the beds underlying the Till. We had therefore no direct evidence to prove that those beds are of the same age as the deposits which lie above them. Having been informed by Mr. John Craig, F.G.S., that a bed of shells had been discovered near Airdrie, much higher than any previously found in Scotland, I considered it of importance to ascertain the exact amount of the elevation above the present level of the sea, as well as the species of the shells, and the nature of the deposit in which they were found. Mr. Craig kindly accompanied me to the locality, which is near the Monkland Iron Works, and about fourteen miles to the south-east of Glasgow. The shelly deposit in question proved to be a bed of the Tellina proxima