Gumbo is clayey soil that is extremely waxy and sticky when wet, as during times of thaw or during or after a rainstorm. Gumbo terrain is referred to as “ape-shit ﬂats” by cowboys on ranches in north-central Wyoming, who are well acquainted with the gooey substance. Early Midwest settlers also struggled with the difﬁcult soil, as indicated by Emmanuel and Marcet Julius Haldeman in their 1921 bestselling book Dust, about farm life in Kansas: “It had rained earlier in the week and Martin was obliged to be careful of the chuck-holes in the sticky, heavy gumbo soon to be the bane of pioneers.” Gumbo is found throughout the south-central United States, where a number of shallow seas once covered wide areas of marine shales and mudstones. Gumbo does have its good uses: the soil makes excellent adobe mud for structures, and bentonite, a type of gumbo created from volcanic ash, is used for well casing and to line duck ponds. A synonym for gumbo is burnout soil.