History of Auglaize County
Belonging to the Blackswamp region the surface features are generally level, broken only by the different natural watercourses, which resolve the surface into bottom lands, second bottom lands, and uplands. The soil of the bottoms, including both river and swamp basins, is an alluvial, deposit usually about three feet in depth. The second bottom soil is, perhaps, shallower and contains a greater admixture of clay, while the uplands consist largely of clay drift with croppings of sand and gravel in different localities. The soil is all very productive, and as yet has yielded abundantly without any fertilizing worth the name.
From "History of Auglaize County, Ohio, with the Indian History of Wapakoneta, and the First Settlement of the County", Robert Sutton, Publishers, Wapakoneta, 1880