Physical properties and spatial controls of stone walls in the northeastern USA: Implications for Anthropocene studies of 17th to early 20th century agriculture

English-style agriculture in the northeastern United States spurred widespread deforestation beginning in the 17th century. Heavy plowing within a rocky, glacial till-mantled landscape resulted in soil erosion and deep frosts. For hundreds of years, stones exposed at the surface due to these processes were built into walls that have become an iconic feature of this landscape, and indicative of past human impacts and land use dynamics in areas that are now reforested. We investigate stone walls in five towns in Connecticut, USA, using airborne Light Detection and Ranging (LiDAR), field measurements, surficial geology maps, and historic agricultural census data. Stone walls are prevalent throughout the study region (∼2113 km over ∼569 km2), but spatial density ranges widely from 0 to 12 km/km2. Important controls on the density of stone walls include surficial materials (e.g., ∼4.0 km/km2 on glacial till compared to 1.5 km/km2 on floodplain alluvium), and whether land had been “improved” for agriculture (∼5.2 km/km2). The length of stone walls derived from analysis of LiDAR data combined with field measurements (average height of 0.76 ± 0.23 m; width of 0.96 ± 0.50 m), indicates that an average of ∼1.4 × 106 m3 of stone was moved for constructing walls in the study towns alone. Overall, this study highlights the spatial distribution of 17th-20th century agriculture and Anthropocene landscape change in the northeastern USA, providing important implications for human-environment studies in other deglaciated regions of the United States and landscapes with stone-rich soils on a global scale where historic agriculture occurred.