Cotton (1942) referred to glaciation as a 'climatic accident' and Pauly (1957) referred to 'world-wide abnormal climates" Such events were regarded as being superimposed on static continents where deep glacial erosion
and deposition of coarse bouldery sediments such as tills simply interrupted an otherwise orderly Davisian cycle of landscape and sediment evolution from youth to maturity.
Given the slight monoclinal southward-dipping (11'-15') bedding of the Palaeozoic sedimentary rocks (Rouk & Raukas 1989), we infer that during pre-Weichselian glaciations Devonian rocks outcropped in the northern part of the drumlin field as well; glacial erosion
has shifted the outcrop area of Devonian sandstones noticeably southward.
Since the summer of 1882, Spencer (no doubt influenced by William Dawson) had become increasing sceptical about the supposed role of continental glaciers in eroding the basins now occupied by the Great Lakes: he then regarded these basins as due primarily to fluvial excavation, modified only slightly by glacial erosion
Sheet structures in granites: Its origin and use as a measure of glacial erosion
in New England.
The geology of the region is by no means only a result of glacial erosion
It is interpreted to have been formed by the concentration of uranium minerals leached from nearby highly radioactive intrusive rocks and deposited in an old riverbed channel which was preserved from glacial erosion
by a cover of younger volcanic rocks.
Based on the above reports, general conclusions can only be drawn: (1) bedrock topography has formed as a result of long-lasting pre-Quaternary continental denudation, (2) deep incisions result from the erosion of ancient rivers, and (3) small undulations in bedrock topography originate mainly from glacial erosion