PORTAGE AND NUNDA QUADRANGLES 69 



between its exposure at Moscow and on the shore of Lake Erie. 

 This westward dip is increased by the thinning out of the Genesee 

 and Portage beds, producing a different rate for each contact line. 

 For the top of the Nunda sandstones the average is about 8 feet 

 per mile with considerable variations due to slight undulations. 



The average southern dip is 20 to 22 feet a mile and toward the 

 south-southwest 30 feet a mile. This appears to be slightly in- 

 creased in some of the quarries, possibly due to the relief from 

 pressure following the excavation of the deep valleys on the sides 

 of which they are located. 



