I am thinking of purchasing a 40s era house that is in Wisconsin. I had an inspector out and everything was good except for a mystery in the basement. The walls appear to be about 2 1/2 ft thick at the base, they are a block and mortar at the base to about 4ft up. Then there is a an angled rubble stone/mortar combination that angles in to about the 7ft mark. The last 10in or so reveals what I am guessing is an original brick wall. There is an open cavity in the 2 1/2 thick area by the chimney, which reveals a loose soil, rubble stone mix filling the void. We were completely stumped. Has anyone ever seen this? Is it fix? something they used to do in the 40s? Would love to hear any theories.