Could this be what we call cob in britain a mixture of clay, straw and horse
dung. It certainly survives in Britain's wet climate if properly maintained
and was common vernacular technigue in the medieval & early-modern period in
many clay areas, though not normally associated with status buildings. It also
occurs as infill in timber framed houses.
paul courtney, Leicester Uk
 
ned heite wrote:
 
This morning, I was reading the 1804 assessment for Mill Creek Hundred, New
Castle County, Delaware, when I saw something startling, to say the least.
Most of the houses in the hundred were stone, or log, or sometimes brick.
Three were listed as mud-walled. What is a mud-walled house doing in
temperate, humid, rainy, wet New Castle County in 1804. In all three cases,
the inhabitants of these mud-walled houses were substantial, one of them a
farmer with more than 200 acres.
 
Turf or sod springs to mind. How else can one intepret this?