(The Rhineland Commission for Archaeological Monuments and Sites, Bonn, Germany)
Keywords: Simulation, Lévy walk, settlement patterns, movement patterns, GIS
The nearly complete list of Medieval settlements in a study area of the Bergisches Land, Germany, and a historical map of 1715 form the basis for analysing the spread of Medieval and early modern farms in this rural region. In this hilly study area with lots of small streams and at best moderately fertile soils, only few archaeological remains of pre-Medieval periods have been recorded, so most probably the population and the number of farms increased considerably during the Middle Ages. Previous studies derived the movement patterns from old trade routes in this region by least-cost path calculations and showed that locations of Medieval settlements are close to the fertile valleys rather than near the old trade routes. A drawback of these studies is that they do not take the size of the settlements into account. Moreover, they are based on static site distribution maps and do not reconstruct the spreading process. Settlement sizes (i.e. one, two, three or four farms, hamlets and villages with a church) are shown on the early 18th century map depicting nearly all Medieval settlements known from historical sources as well as a small portion of additional settlements. The first step in reconstructing the spreading process is to identify patches for subsistence, i.e. possible locations of Medieval and early modern farms. Different hypotheses with respect to the origins of the spreading process are investigated by simulations. The search for a subsistence patch is modelled by an approach similar to Lévy walks adjusted so that they take the known movement patterns into account. A spreading procedure is considered to reconstruct the settlement process successfully, if the final distribution of farms is close to that recorded on the map of 1715.