THE GEOLOGY OF THE SYRACUSE QUADRANGLE 41 



times this elevation. The lowest point on the area is 360 feet, thus 

 giving a maximum relief on the area of the quadrangle of approxi- 

 mately 640 feet. 



CHANNELS 



The northern edge of the plateau is a somewhat bold limestone 

 escarpment very irregular in contour. The north-flowing Onon- 

 daga and Butternut creeks have cut deep valleys or trenches in 

 the plateau, thus dividing the escarpment on this quadrangle into 

 three parts. Smaller streams have cut notches between the larger 

 creeks thus giving the escarpment a jagged as well as broken 

 appearance. 



In addition to the north-south valleys, the north end of the plateau 

 is diversified by a number of east-west valleys or trenches across 

 the interstream areas, some of which are of considerable size and 

 interest; some of them near the escarpment have separated consider- 

 able masses or outliers from the plateau, thus adding to the diversity 

 of the relief. 



The peculiar interest attached to the east-west valleys is that they 

 were formed in large part by temporary streams sometimes of large 

 size during the closing part of the Pleistocene glacial period and thus 

 become fossil pleistocene channels. During the recession or melting 

 away of the continental ice sheet, there came a time when the south- 

 ern end of the ice was in the vicinity of Syracuse and the waters 

 from the melting ice and from the plateau having no outlet north- 

 ward through the St Lawrence valley as at present, found an escape 

 eastward through the Mohawk valley. This eastward flow from 

 the Onondaga valley to the Butternut and from the Butternut to 

 the Limestone valley caused the erosion of a number of deep chan- 

 nels across the ridges separating the north-south valleys. The first 

 of these channels formed on the area of the Syracuse quadrangle 

 is about 3 miles south of the city and over 1 mile north of James- 

 ville. It is known locally as the Railway channel, as the Delaware, 

 Lackawanna and Western Railroad passes through it. The channel 

 is about 3 miles long and a quarter to a half of a mile wide. The 

 floor of the channel is 150 to 250 feet below the level of the plateau 

 in which it is cut and the western end is 150 feet above the bottom 

 of the Onondaga valley and the eastern end about 80 feet above the 

 level of the Butternut valley. It thus forms a unique type of hang- 

 ing valley, that is, one that hangs at both ends. 



During the time when the water was flowing eastward through 

 the Railway channel, the ice front was probably near the north bank 



