Figure 25: Sketch of decay/erosion and formation processes. At the top, a hypothetical cross-section of buildings, with two storey structures on either side of a narrow street (centre); below, after erosion/collapse. The debris from the two storey structures alongside the street creates more substantial mounds of debris, larger than the smaller structures. Despite the collapse of elements in the two-storey structures into the street, the space is still evident as a pronounced linear hollow.