The origin of certain white or gray clays or silts found on the flat upland surface of the Illinoian drift in southern Ohio and also on residual soils in a similar position outside the glaciated area has been in dispute for the last fifty years. It is the purpose of the present paper to show that these white clays are due to the weathering on upland flats of the upper two feet or so of the mantle rock, whether that mantle rock is till or residual soil derived from either limestone or sandstone.
There has been no attempt in the present paper to go into the details of the chemical changes involved in the production of the white surface clays or soils. Recent soil studies have shown “that soils pass through cycles of development, . . . that there are young, mature and old soils.” 2 Lyon and Buckman3 . . .