from Portage to Nnnda, filled up by drift, compelling the river to cut its present deep, tortuous 

 channel. For other examples of this see notes 31, 35, 38 and 39. 



111. Avon. You have 6. Waterlime, 9. Upper Helderberg, and 10 a. Marcellns shale in the creek. 



112. To study the Genesee shales stop at Mount Morris. Go through the village one mile north- 

 west to the mouth of the gorge, where the Genesee River, after running 20 miles through the deep 

 canon from Portage, breaks out into the beautiful, broad and fertile Genesee Valley. There is a 

 good section close to the bridge over the river. Get a boat and row one mile up the pool of the 

 State dam, which flows to the foot of the precipices all that distance. This is the finest exposure of 

 the 10 c. Genesee in the State, the typical locality from which it was named, and the scenery is in 

 itself remarkably good. The cliffs are 100 to 200 feet perpendicular, full of septaria, like flattened 

 cannon balls sticking in the walls. It is carious that so soft a shale rock should stand the weather 

 so well and not form sloping banks when the edges only are exposed. See note No. 110, Portage. 



. 113. Dansville is in a beautiful amphitheatre of Portage hills with very picturesque views from 

 the Water Cure and other elevated points. 



114. The Rosendale Cement, manufactured near Rondout, is from the 6. Waterlime rock, 

 which is here between the Medina sandstone and the Lower Helderberg limestone, the intermediate 

 formations being wanting. It is a light blue, fine grained limestone, with smooth conchoidal fracture. 

 The same formation furnishes the Hydraulic Cement, made at Syracuse, N.Y., and elsewhere. 



115. Jamestown. Chatauqua Lake is 18 miles long, 2 miles wide, 1291 feet above tide water and 

 726 above Lake Erie. Its northern extremity is only 8 miles from Lake Erie, and yet it empties its 

 waters by the Conewango, Alleghany, Ohio and Mississippi into the Atlantic. It is a beautiful sheet 

 of water, bounded on its eastern side by gravelly sloping banks, and on the west by more levej and in 

 some places marshy shores. It is excavated in the Chemung group, the Portage being along its 

 outlet and on the shores of Lake Erie below, but of much less thickness than further east. 



