6 research outputs found
Early glaciological and Quaternary Geology cooperation
Get PDFThe article depicts the author’s experiences of Glaciology and Quaternary Geology research between Finland and the People’s Republic of China. The focus is on a visit to a glaciological station in Tianshan in 1988. The climate is continental displaying warming-up and increased precipitation since the end of the 1980’s. The data collected here is of utmost importance when analysing the future development of the glaciers. Some associations to the historic Silk Roads are made having implications on the Belt and Road strategy launched by the Chinese. As to problems of sea and lake ice, Finland and the P. R. China have found issues of mutual interest resulting in continuing cooperation in the Arctic and in ice-covered areas of China. New forms of bilateral collaboration such as university education and training have evolved encompassing coming generations
De Geer moraines in Finland and the annual moraine problem
No full textThe study has two main aims: (1) a description of the characterizing features of the morphology, material structure and mode of occurrence of De Geer moraines in Finland, and (2) conclusions about the depositional mechanism and the geoÂchronological significance of the moraines. Thereby, it strives towards a defiÂnition of the term 'De Geer moraine'. In doing so, both the previous term 'anÂnual moraine' and the use of these landforms in deglaciation reconstructions are examined. Main field investigation methods included petrographic, granulometric, morÂphometric and two‑ and three‑dimensional orientation analyses, carried out in the study area in Hyvinkää and other important occurrence areas. Distances between successive De Geer moraines in Finnish moraine fields were measured cartometrically, and the values later combined with corresponding information on moraines in, above all, Sweden and Canada. Seasonal rhythm in moraine disÂtances is found only exceptionally by comparison with clay varve data on the ice‑marginal rate of retreat. The common average distance between De Geer moÂraines in Finland, approximately 100 m, does not reflect successive positions of the ice margin during the course of deglaciation. Neither do the deposits show any other features typical of end moraines. All De Geer moraines of any demarcated group of ridges were deposited alÂmost simultaneously during a quiescent phase of ice flow, as the ice subsided into a water‑soaked subglacial layer of till. The basal crevasses, formed during the previous quick flow of the ice mass, were filled by material resembling ground moraine being squeezed up from both sides into the cavity. The material redisÂtribution resulted in very similar average distances in all moraine fields. CondiÂtions were particularly favourable for so‑called glacial surges within a 10–15 km wide zone inside the ice margin in the vicinity of interlobate areas, exceedÂingly rich in melt‑waters. Long‑axis orientations of De Geer moraines thus indiÂcate the influence of both substratum and subglacial drainage systems on basal crevasse development. The deposits – kinds of 'crevasse fillings' – were not deformed by subsequent ice flows, as the ice front was usually broken up by a considerable body of proglacial water
