While this barrier was unbroken, Lake Erie as extended would have covered all land that was not twenty-six feet higher than the present level of the river at old Schlosser landing, since the water there is sixteen feet below the level of Lake Erie. It is not difficult to trace this barrier on a good map. From old Fort Grey it stretches eastward a short distance past Batavia, and thence turns to the south through Wyoming into Cattaraugus County. In the latter county it forms the summit level of the Genesee Valley Canal. This summit is a swamp sixteen hundred and twenty-three feet above tide water, and the water runs from it northerly through the Genesee River into the Gulf of St. Lawrence, and southerly, through the Alleghany, into the Gulf of Mexico, while within a short distance rises Cattaraugus Creek which flows west into Lake Erie. The gradual rise of the Niagara barrier as it extends to the east was demonstrated by the surveys of Captain Williams. By the Gill Creek line to Lewiston he found its elevation above the river, as has been stated, to be sixty feet. By the Cayuga Creek line to Pekin it was sixty-four feet, and by the Tonawanda Creek line to Lockport it was eighty-four feet, as is also shown by the surveys of the Erie Canal. To the west the barrier extends from Brock's Monument to the ridge which bounds the westerly side of the valley of the Chippewa Creek, and thence around the head of Lake Ontario into the Simcoe Hills. At that period all the islands in the Niagara River valley were submerged. The lower sections of the valleys of the Chippewa, Cayuga, Tonawanda, and Buffalo creeks were also submerged. The site of Buffalo was, probably, a small island, and many other similar islands were scattered over the broad expanse of water.