Glacial Erosion in France, Switzerland and Norway

Early Discoverers XXXVI: W.J. McGee On Glacial Erosion Laws and the Development of Glacial Valleys

“…Forbes, 1853), but typical explanations of this frequent discordance in elevation between tributaries and main valleys in alpine areas were couched in terms of recent river rejuvenation as a result of regional uplift. During the hypothesized uplift period, the main rivers, with greater discharge and thus erosive ability, could cut down more quickly than their tributaries, leaving the tributaries progressively "hung up" above the main rivers (see Davis' (1900) review of the work of Reuss and Heim in the 1860s and 1870s). Although Davis (1900) credited McGee (1883) with the first explicit glacial explanation for hanging valleys, McGee's work came several years after Hellands's (1877) clear analysis of the problem:…”

The Geomorphology of the Glacial Valley Cross Section

“…Several subjective studies have previously been made of the valley cross sections of alpine glacial valleys (Harker, 1899;Davis, 1900Davis, , 1906Davis, , 1916Hershey, 1900;Coleman, 1913;Crosby, 1928;Lewis, 1947). From the first statement by McGee (1883) to the more recent works on the subject (e.g., Flint, 1957, p. 94), the term U-shaped has been commonly used.…”

Early Discoverers XXXVI: W.J. McGee On Glacial Erosion Laws and the Development of Glacial Valleys

“…4). This latter aproach, involving reconstructing pre-glacial valleys assuming initially graded junctions, was favoured by Davis (1900) and Matthes (1930), and produced results that, perhaps more than any other line of evidence, provided confirmation of the significance of glacial erosion to geologists in the early twentieth century .…”

“…In the latter half of the nineteenth century, there was fierce debate over whether glaciers were even capable of significant erosion, so it is perhaps not surprising that McGee's analysis of glacial erosion processes and land-form development received little attention in his own time. Despite this, McGee's work provided some of the first really convincing glacial explanations for the development of land forms such as hanging valleys and U-shaped valleys, and these were developed more fully in later work by Davis (1900) and Gilbert (1903). In modern research, the use of theoretical erosion laws and a knowledge of ice dynamics to develop models of land-form development is emerging as a major theme in glacial geomorphology , marking a return to the methodology pioneered by W.J.…”