Leverett — ■ Weathering and Erosion as Time Measures. 359 



European Correlatives f of the Illinoian Drift. 



From their position in the series one would naturally expect 

 to find correlatives of the Illinoian drift in the Middle Dilu- 

 vium of north German lowland and the Riss drift of the 

 Alpine region. But neither the Riss nor the Middle Diluvium 

 was found to bear a close resemblance to our Illinoian drift. 

 These European drifts are commonly weathered to a depth of 



Fig. 4. 



Fig. 4. Part of the Belleville, Illinois, quadrangle, showing Post-Illinoian 

 drainage under a very low stream gradient. Compare the small amount of 

 dissection of the drift plain with that in fig. 3. Scale, 1 : 93700. Contour 

 interval, 20 feet. 



only 3 or 4 feet and there is a very abrupt change to fresh- 

 looting drift at the base of the weathered portion. Were the 

 upper part to the depth of a meter stripped off from these 

 drifts one would find difficulty in distinguishing the Kiss from 

 the Wiirm, or the Middle Diluvium from the Upper Diluvium. 

 The induration of the deeper portion, so generally found in 



