Geoscience Reference
In-Depth Information
Chapter 3
Glacial Erosion/Sedimentation of the Baltic
Region and the Effect on the Postglacial Uplift
Aleksey Amantov, Willy Fjeldskaar, and Lawrence Cathles
Abstract
Plio-Pleistocene erosion and sedimentation significantly impact post-
glacial uplift. We estimate in the last glacial cycle sedimentation could produce up
to 155 m of subsidence and erosion 32 m of uplift. To show this we determine
the changes in surface load caused by glacial and postglacial erosion and sedi-
mentation over 1,000 year time intervals (coarser intervals before 50,000 years)
utilizing a largely automated interpretation of regional geological and geomorpho-
logical observations that is constrained by plausible bounds on the rate of erosion
of various lithologies and the known general pattern and behavior of glacial ice
(ice boundaries over time, the dendritic pattern of ice movement, geometry of fast-
flowing ice streams, plausible changes in frozen-bed conditions, etc.). Mass balance
between erosion and deposition is enforced at all times. The analysis is regional and
obliged to agree with all known geological constraints. Although the focus is on
the last glacial cycle, all previous cycles are considered. The analysis suggests that
the first glaciations probably shaped the major overdeepened troughs, although it
is possible that the deepening was distributed evenly over all the cycles. Younger
glaciations mainly removed sediments left by their predecessors, decreasing the
thickness of the Quaternary succession and only locally incising and changing the
dip of the bedrock surface. Over the last glacial cycle, ~20-90 m of sediments (and
locally more) was removed in the zones of most active erosion.
Keywords
Pleistocene
·
Glaciation
·
Erosion
·
Sedimentation
·
Isostasy
·
Fennoscandia
·
Baltic
·
Ice-stream
·
Uplift
·
Bedrock
3.1 Introduction
The role of glacial erosion and sedimention in creating the modern landscape of
the Baltic Sea basin has been appreciated for a long time. Glacial and fluvioglacial
erosion had a decisive influence in shaping the Baltic-White Sea lowland on the
