Using northern Vermont as an example, we demonstrate that the sedimentary record preserved in humid-region ponds and alluvial fans can be dated, deciphered isotopically and stratigraphically, and used to understand the history of hillslope erosion. Our data suggest that erosion rates were higher in the early and late Holocene than in the mid-Holocene, perhaps the result of changing climate and the frequency of severe storms. In Vermont, dated alluvial fan sediments reveal that the highest rates of hillslope erosion occurred as a consequence of European settlement. The geologic record of colonial deforestation is clear, revealing significant human impact and suggesting that past landscape response is a meaningful basis for guiding future land management practices. On the Efficacy of Humans as Geomorphic Agents Roger Hooke, GSA Today, vol.4, no. 9, September 1994.
Humans are geomorphic agents.
They move vast quantities of soil and rock, and have a major visible impact on the landscape. To place this impact in perspective, I have compared humans with mor traditional geomorphic agents on the basis of the mass of material moved per year. In most instances we can identify a line, such as the coast, across which this material is moved. For example, the annual sediment load delivered to the oceans and interior basins by rivers is about 24 Gt, and during the Pleistocene, glaciers probably deposited about 10 Gt of til in moraines and outwash fans every year. In the case of humans, movement of material is more random, so it is not possible to identify such a line.