326 



Report of the State Geologist. 



mately thirty feet below the level of the canal tow-path. Across the river, 

 the limestone in sight is water-worn but not glaciated. The highest outcrop, 

 how ever, is not more than five feet above the mean surface of the river. It 

 may be assumed, therefore, that the present channel of the Niagara river at 

 this point existed before the glacial epoch, and was at least twenty feet below 

 the surface of the limestone cliff on the eastern side, and probably lower near 

 the middle. 



Ha]f a mile down the river on the Canadian side, near the stone church, 

 the water -lime is striated and smoothed by glacial action down to and beneath 

 the water line of the river. Photographs showing these markings and those 

 in the quarry on the American side are here given. It is certain, therefore, 

 that the present channel of the upper Niagara cannot be more recent than the 

 close of the glacial period, and probably was well defined to the depth of 

 twenty feet or more before that time. 



The rate of erosion going on now is difficult to estimate, very few data 

 upon that point having been collected. In smaller streams flowing over the 

 Corniferous limestone, the amount of erosion since the glacial period amounts 

 t<> only a few inches. A view of the bed of Cayuga creek, near Bellevue, is 

 inserted here for the purpose of illustration. The surface of the limestone 

 under the bridge is glaciated on the right bank of the stream. Erosion lias 

 proceeded through the widening of joints, partly by the action of water, and 

 partly through the agency of material carried along by the current. The 

 stream is here quite rapid when at its normal height, but the depression in 

 the channel shows that very little material has been removed. While the 

 volume of water in the Niagara river is much greater than in the stream 

 referred to, it is probable that erosion is there proceeding very slowly; and 

 that a part of the central depression, where the river now is, was excavated 

 before glacial time. 



Preglacial Rivers. 



It has been thought by Dr. Julius Pohlman and others, that a preglacial 

 liver of large size flowed into the depression now occupied by hike Erie at 

 some point between the present mouth of Buffalo creek and Bay View. 

 This opinion was based largely upon the fact that in driving piles for the 

 Lehigh docks on the Tifft farm, the bed-rock was found to suddenly drop 

 from abouf thirt \ -seven feet to over a hundred feet below the surface. As 

 the rock to the northward was known to be Corniferous limestone, it was 

 argued that a stream of Larger size than Buffalo creek was necessary to erode 



