Using a combination of the two diggers, it took anly about a day and a half to excavate the levels down to sold rock almost all the way across the lower floors. It was a great relief that the level of the rock followed the slope of the ground, because once one part of the foundatons are on solid rock, one has to dig down to find solid rock for the rest of the foundations. It was in fact so close to the surface that the foundations could be more shallow than they would have been on clay or sandy loam. In the end no changes to design were necessary.
