Marina gränsen i Västra Sverige

This investigation is an analysis of some problems of the Marine Limit (MG) in Western Sweden. As MG has been formed as the dividing-line between the sea and land-area in Late-Glacial time, it can be defined either as the highest level of the sea or as the lowest line of the land-area. In the former case it can be determined as the uppermost limit of marine abrasion or of stratified drifts, especially outwash plains, rarely eskers or other fine deposits, such as silt or shore-dunes. In the latter case it is the lowermost line of marginal drainage channels or certain glacial drifts such as ablation moraines. In theory, but in fact only exceptionally, it might be the highest limit of salt-water deposits. Morphologically three types of MG can be distinguished. Usually it is a simple notch, with or without pebbles and situated a little above the uppermost real marine beach. Very often, but only for short distances, it is formed as a distinct terrace and in such a case it is in fact the highest marine shore plain. In the third case it is the best-defined of all the beaches and is a very marked notch or zone of boulders. Generally MG rises successively northwards, i. e. with increasing intensity of the land-upheaval. In details, however, it is more complex and is composed of long sections with great gradients and short ones with small gradients. In the former case MG is metachronous and morphologically of type one; in the latter case it belongs to isochronous shore plains and is formed of type two. The middle gradient is 0,20–0,25, 0,40–0,45 or 0,55, 0,60‰. Sometimes, however, MG rises with a gradient of 0,90–1,00‰ and after the culmination it falls again. These discontinuities are called MG-anticlines and are due to isostatic retardations, implying three components: a short submergence, a short stand-still and then a probably very rapid emergence. Three of them can be observed in Western Sweden, one from the Late-Gothi-Glacial time (G1), one between the Gothi- and Fini-Glacial time (GF) and one from the earliest Fini-Glacial time (F). All these periods are characterized by very important stagnations. But even the general course of MG can indicate the size and rapidity of the ice-recession and thereby indirectly the climate: small gradients = slow retreat = severe climate, great gradients = rapid recession = more warm climate.

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