IMPACTS OF TERRAIN ROUGHNESS ON 18TH-20TH CENTURY LAND USE DISTRIBUTION AND SEDIMENT MASS TRANSFER IN SOUTHERN NEW ENGLAND

The topography of Connecticut varies broadly with rugged hills >700m elevation in its western corner, to the broad, gently sloping Connecticut River valley and coastal regions in the south. The land surface varies between being soil mantled and smooth to rocky and rugged due to the dominance of glacial moraine deposits. This study, situated in northwestern Connecticut, uses publicly available LiDAR data with an average point spacing of 0.7 to 2 points per sq. meter to examine how terrain roughness at varying scales in conjunction with surficial geology influenced historic land use decisions. We find that terrain and associated soils impacted the initial types of husbandry that were practiced by the English after their colonization of the region in the early 17^th century. The distribution and presence/absence of stone walls and relict charcoal kilns appears to have been highly influenced by the slope and roughness of the land surface at both regional scales and scales of individual perception. These findings are consistent with historic agricultural journals, books, and anecdotes that advocated using steeper slopes for pasture or woodlots, because steep tilled slopes exacerbated erosion and caused already-marginal soils to deplete quickly. English land use was drastically different from that practiced by Native Americans, and included widespread deforestation, as well as the removal of large stumps and stones from cleared fields to enable deep plowing. These two factors drastically increased erosion on upland hillslopes, and also led to deeper freeze-thaw cycles of the ground surface, allowing more stones to rise and be cleared to field edges. In just 2 towns in northwestern Connecticut, with a size of approximately 236 sq. km combined, there are over 800 km of stone walls. On steeper slopes we find relict charcoal kilns; flat earthen platforms approximately 10-16m in diameter that are often reinforced with stone and used for producing charcoal for nearby iron furnaces. These land use decisions were clearly influenced by the terrain, show a mass transfer of geologic material over this time period, and can be considered a proxy for identifying areas of probable erosion and soil or landscape change.