Pre-glacial Channel in Ohio and Indiatia. — Bownocker. 1 79 
one of which empties into lake Erie and the other two into 
the Ohio river. The rivers are the St. Marys, which, flowing 
to the west and north, unites with the St. Joseph to form the 
Maumee, the Great Miami which flows to the southwest, and 
the Wabash which, first pursuing a northwest course, turns 
to the southwest and empties into the Ohio. The Wabash 
and St. Marys rise in the territory under consideration, while 
the Miami rises in an adjoining county. Considerable of the 
locality under consideration is really a watershed separating 
the three named rivers. Situated near the middle of the terri- 
tory is the Grand reservoir vvhich covers about 17,000 acres, 
and is said to be the largest artificial body of water in the 
world. 
The rock floor on which the drift lies is everywhere the 
Niagara and Lower Helderberg limestones. It was on the 
pre-glacial soil which covered these rocks, and in channels 
cut in these limestones that the pre-glacial streams flowed. 
When the great ice sheet advanced over this region it com- 
pletely filled the valleys which it found, and deposited the 
mantle of drift. When the glacier receded it disclosed a new 
topography; the old valleys were deeply buried, and a low 
watershed was formed across the territory. Consequentlv a 
new drainage system developed, and this, as will be shown, is 
radically different from the pre-glacial one. 
The course of the old drainage line has been disclosed bv 
the driller for oil and gas. To him we are indebted for the 
follovv'ing facts: At Anna, Shelby county, Ohio, 514 feet of 
drift were passed through. Within a mile east or west of 
this place the drift does not probably exceed 150 feet in depth. 
At Anna the old stream had cut entirely through the Niagara 
and Clinton limestones and into the Aledina or Hudson shales. 
Running northwest to the Auglaize county line successive 
wells showed depths of drift of 320. 400, 440, and 440 feet, 
while the drift outside of, but near the channel nowhere ex- 
ceeded 140 feet. Passing into Auglaize county and running 
toward the Grand reservoir successive wells showed depths of 
drift of 190. 380. 370, 370, 370, 370. and 370 feet. The shal- 
lowness of the first well above given is probably due to the 
well's having been put down near the margin of the channel. 
The depth in this locality outside of the channel ranges from 
