Beginning northeast of Upper Sandusky in Wyandot, looping along the southern county boundary, entering Hardin County along its northern border with Hancock County. The moraine then runs, west of southwest to the moraine runs, southwest to Lima. From Lima it runs west and northwest along the right bank of the St. Mary's River to Ft. Wayne. Continuing northeast on the left bank of the St. Joseph River to Hudson, Michigan in Lenawee County. The moraine is or wide and has an undulating surface. Its main crest is to above the beds of the rivers that follow the outer border. The rivers are in trenches to deep. The moraine is to above the bluff or plain. The wide outer slope of a mile or more provides any local relief. The drift is a clay till and has boulders.
St. Mary's (south) Unit
The presence of the moraine is evident in the course of St. Mary's River. Its headwaters in Auglaize and Mercer counties, flow north toward the Maumee until it comes to the moraine ridge. Here it turns to the west. The ridge forms the watershed between the St. Mary's and the Auglaize River. It is about from the St. Mary's and the Auglaize. In Allen County, Indiana the Wayne trace, or old Piqua road follows the crest. The inner slope is gentle, while the outer slope is steep. On the west side of Six Mile Creek gap the moraine is a bold bluff to high to the point where the Wabash and Erie Canal once crossed the St. Mary's. The summit is above the mouth of the St. Mary's. The ridge is composed chiefly of boulder clay with a border of sand and gravel around its northern end.
St. Joseph (north) Unit
North of Fort Wayne the moraine is simple in structure. It extends from Ft. Wayne along the left bank of the St. Joseph River into Michigan. Through Indiana it is four miles wide and gets broader through Ohio and Michigan. It rises from to above the Maumee Lake bed.
Outliers
The plains to the east between the Fort Wayne and Defiance is wide and is occupied by faint terminal moraines. These are closely related to the Fort Wayne moraine. Two moraines run parallel with the main crest of the Fort Wayne moraine in the vicinity of Lima, Ohio. The Bluffton moraine is west of Mount Cory to Bluffton and then turns southwest to within a mile of Cairo and Elida. The Rawson moraine runs west from Rawson and curves to the southwest roughly parallel with the Bluffton moraine some 2 or 3 miles north. A third significant ridge runs across Allen, Van Wert and into Adams and Allen counties. East of Landeck, southwest of Delphos, the ridge is indistinct through Venedocia, to the Auglaize River, northeast of Southworth. West, the ridge is distinct Monroeville, Indiana. Through Indiana the ridge is a double crest. North of Glenmore the moraine turns northwest. This ridge is later than the Bluffton moraine, and may be a westward continuation of the Rawson moraine.
