GLACIAL BOUNDARY IN OHIO. 755 
thence running to Sag Harbor and Canoe Place, and due west to Harbor 
Hill, at Rozlyn, the highest point in the island, thence west southwest 
through Greenwood Cemetery, Brooklyn, to the Narrows at Fort Hamil- 
ton and across the southeastern part of Staten Island. 
About the same time (1876-77) Professors Cook and Smock, of New 
Jersey, accurately mapped the moraine across that State. Beginning at 
Perth Amboy, it bends northward through Raritan, Plainfield, Chatham, 
Morris, and Hanover to Rockaway, thence a little south of west to 
Belvidere, on the Delaware, a few miles above Haston. 
From that point, leaving the Delaware at Belvidere, about fifteen 
miles above the mouth of the Lehigh, the glacial boundary crosses 
Northampton county by a general northwestern course to the centre of 
Monroe county. Here it turns westward, crossing the Lehigh at Hickory 
Run, about fifteen miles above Mauch Chunk, and continues westward 
until it crosses the east branch of the Susquehanna, at Beech Haven, 
about twenty miles below Wilkesbarre. Thence by a northwesterly course 
it continues through Columbia county, rising upon the summit of the 
Allegheny Mountains, and crossing them diagonally in Lycoming 
county ; thence (still northwest) through Tioga and Potter counties into 
Cattaraugus county, New York, reaching its most northerly point at 
Little Valley, six miles north of Salamanca. Thence it runs in a pretty 
direct southwest course to Columbiana county, O. 
The accompanying map of Ohio shows the glacial boundary ex- 
plored by me during the summer vf 1882. This does not, as some may 
have surmised, represent merely a line which I have traversed, but a 
line which I have zigzagged, and along which, I believe, I have 
determined with tolerable certainty the glacial boundary upon nearly 
every mile of its course. In every township I have endeavored to go 
far enough south of the line, here marked, to make it sure that I was 
beyond the limit of glaciation. Down to this line the marks of glacia- 
tion are everywhere abundant and unmistakable ; south of it the absence 
of glacial marks is equally striking. 
The glaciated area of Ohio consists of a rolling surface essentially 
like the prairies farther west, except that it was originally covered by 
timber. ‘The preglacial channels have nearly all been buried out of 
sight, and it is rare that the rocks anywhere emerge above the till. The 
till itself contains everywhere glaciated fragmerts of a great variety of 
rocks, all of which are from the north. It is not unusual to find, in 
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