GLACIAL WATERS IN THE LAKE ERIE BASIN 'JJ 



proof of the recent tilting of the land surface. In other sections 

 ■of the continent land warping may take place without any visible 

 indication of the movenient, but in this area of the Great Lakes 

 the deserted shores of the "fossil lakes" supply a delicate test 

 •and measurement of the land deformation. The important element 

 in the determination of the fact and of the amount of the deforma- 

 tion is the identity of the shore line or water level. In far separated 

 localities this ma^^ be in doubt but in the region described in this 

 writing the continuous tracing of the beaches leaves no uncertainty. 



In calculating the amount of deformation in our district some 

 care is necessary, for several reasons: first, because the amount of 

 deformation is small; second, because the shore features are 

 variable ; third, possible discontinuity of the water planes \see p. 70] ; 

 fourth, errors in railroad or other data. The best data for fixing 

 the water levels are the crests of the wave-built gravel bars. Un- 

 doubtedly these are variable within narrow limits, some having 

 been formed higher than the lake surface and some lower, Or 

 submerged. The higher and stronger and coarser of the marginal 

 bars may be safely regarded as overtopping the water by a few 

 (perhaps 5) feet. The lower bars in each cross-section were sub- 

 merged an uncertain and variable depth and are not reliable data, 

 at least for short distances. The stronger and higher marginal bars 

 are more reliable criteria, and in long distances their variations may 

 be neglected. 



By using the Whittlesey and the stronger upper Warren bars 

 in our calculations it is found that the average amount of differential 

 uplift in our district is less than 2 feet a mile, but that the amount 

 of tilting a mile increases as we pass to the northeast. The facts 

 ■are given quantitatively in the following statement. 



DEFORMATION IN NORTHEAST DIRECTION, USING WHITTLESEY BEACHES 



From State Line to Marilla, 90S — 783 feet=i22 feet, --74 miles=i.64 feet 



rise a mile 

 State Line to North Collins, 850 — 783=67 feet, -^ 48 miles=i.4 feet a mile 

 State Line to Fredonia, 820 — 783=37 feet, -=- 26 miles=i.4 feet a mile 

 Fredonia to North Collins, 850 — 820^30 feet, --22 miles=i.4 feet a mile 

 North Collins to Marilla, 905 — 850^55 feet, h- 26 miles^2.i feet a mile 



DEFORMATION IN NORTHEAST DIRECTION, USING WARREN BEACHES 



State Line to "Pond" Survey station, 887 — 738=149 feet, -- 92.5 miles= 



1. 6 1 feet a mile 

 State Line to north of Marilla, 860 — 738=122 feet, -=- 75 miles=i.63 feet a 

 . mile 

 Westfield to "Pond" Survey station, 887 — 753=134 feet, -- 81 miles=i.65 



feet a mile 

 Westfield to Fredonia, 770 — 753=17 feet, -f- 15 miles=i.x feet a mile 

 Fredonia to Hamburg, 807 — 770=37 feet, -j- 31 miles=i.2 feet a mile 

 Hamburg to Crittenden, 858 — 807=51 feet, -=- 24 miles=: 2.1 feet a mile 

 Crittenden to "Pond Survey" station, 887 — 858=29 feet, -h it miles=2.6 



feet a mile 



