Soil aspects affecting archaeological details in aerial photographs
Helge Stanjek, Jörg W. E. Faßbinder · Archaeological Prospection · 1995
Archaeological details on aerial photographs become visible as crop, soil, or snow marks. For the occurrence of crop and snow marks, differences in bulk density are identified as the main soil factor, because bulk density determines the water balance and thermal behaviour. Bulk densities and pore size distributions were measured at different sites. Pore size distributions of archaeological structures in loess soils do not differ from surrounding B horizons, which explains the rareness of crop marks on loess soils. On gravel soils, however, changes from positive to negative crop marks were observed within a few weeks. They are explained by the interplay between plant available water, plant growth and evapotranspiration.