Fennoscandia: Glacial landforms prior to the Last Glacial Maximum

Much of the pre-Last Glacial Maximum (LGM) geological record in Fennoscandia lies in sediment stratigraphic sequences. Indeed, early views of Fennoscandian glacial history (particularly for the pre-LGM period) were largely based on litho- and biostratigraphic correlations, while glacial landforms were considered to belong only to the last ice sheet maximum position and deglaciation. The richest stratigraphic sequences, where multiple tills record repeated growth and decay of Quaternary ice sheets, lie in (1) the ice sheet marginal zones, where sediment accumulation is favoured, and (2) in the interior zones of the ice sheet domain where cold-based ice has been prevalent, and where landscape preservation is favoured. In both cases, glacial deposits as old as the Elsterian (likely Marine Isotope Stage 12) have been interpreted. Widespread recognition of cross-cutting landforms has prompted reassessment of both ice sheet history and landforming processes. While landforms predating the LGM are rare at the southern margin of Fennoscandia, they are surprisingly plentiful—albeit fragmentary in distribution—in the domain interior as a consequence of cold-based and minimally erosive ice over successive ice sheet growth and retreat cycles. These landforms cover the full spectrum of glacial geomorphological environments from subglacial to glaciofluvial to ice marginal and supraglacial. Here we outline the distribution and key characteristics of Fennoscandia’s glacial landscapes that predate the Last Glacial Maximum.