The Cirque Forms of Central Sweden

ABSTRACT

The present paper on cirque forms in Central Sweden deals with a survey, which in its turn is a continuation of a corresponding one of cirque forms in Swedish Lapland (Vilborg 1977). Compared with the latter survey the now used cirque form classification system has been slightly changed and—hopefully—improved.

About 550 cirque forms have been mapped within a surveyd area of ca 110 000 km², practically all without glaciers. However, only 16% of them are interpreted as fairly credible glacial cirques. The regional, as well as the vertical and aspect distributions of these cirque forms have been briefly examined. On the whole, the various distribution patterns can be explained in the light of general land relief, relative relief of land surface, the orientation of more pronounced mountain crest/ridges, fracture zones of regional persistance and some further variables.

Special interest has been payed to mountain areas with many cirque forms in relation to adjacent areas of about the same altitude, almost lacking cirque forms. Rock type seems to be at least one differentiating factor. Some comments are also made on indications of so-called cirque stairways with regard to their appearance and location.

About 50 cirque forms are situated outside the mountain region, at comparatively low levels. They indicate a conspicously great depression of the glaciation level(s) during Pleistocene if the interpretation of them as glacial cirques will prove to be correct. A few specimens are described more closely.

In the light of the cirque form distribution patterns of Lapland and Central Sweden some reflections are made on the optimum cirque formation periods. Are the initial stages of the Pleistocene glaciations necessarily those periods when the majority of the best developed Swedish glacial cirques had their main backwall retreat and downward cutting-out?