Function of the ice streams in the Scandinavian ice sheet: analyses of glacial geological data from southwestern Finland

• Published in: Transactions of the Royal Society of Edinburgh: Earth Sciences
• Main Author: Punkari, Mikko
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1994
• Subjects: Paleontology; Earth and Planetary Sciences (miscellaneous); Ice Sheet
• Online Access: http://dx.doi.org/10.1017/s0263593300002054; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0263593300002054

Abstract Mapping of striae trends, macro-scale erosion forms, drumlins, morainic ridges, eskers, till fabric and boulder fans has facilitated reconstruction of glacial dynamics in terms of ice streams, marginal ice lobes and interlobate zones. Data were recorded in a computerised geographical information system (GIS). Data on oriented glaciogenic elements are compared with the evolving patterns of glacial flow. The oldest flow occurred at a distance of several hundred kilometres inside the ice margin, while the later flows were dependent on the dynamics of the ice streams and fan-shaped ice lobes. A model is developed for the zonation of subglacial processes such as erosion, deposition and till deformation beneath the ice sheet. Most of the glacial forms, as well as lower till, were generated in a zone of basal melting and fast ice flow which existed some hundred kilometres from the receding margin and was associated with the formation of ice streams. These results are consistent with recent reconstructions of basal hydrology using mathematical models. Ice streams were important for deglaciation dynamics. In the course of deglaciation, decreased shear stress on the water-saturated substratum resulted in ice-bed uncoupling which lowered the profile and accelerated flow in the ice streams. This did not happen in interstream areas as reflected by the glacial geomorphology typical of inactive ice.