60 Gf 5 . REPORT OF PROGRESS. I. C. WHITE. 



The question of the propriety of including or excluding 

 the upper transition beds in this estimate is left open ; but 

 there is certainly no such strong and decided break in the 

 whole series of 2740' from the base of the Pottsville con- 

 glomerate to the base of this Catskill series, .as occurs at the 

 base of the Pottsville. 



The only notable difference between this series and those 

 above it, already described, consists in a greater percentage 

 of red rocks. But in none of the exposures does it exceed 

 40 per cent. ; often not 20 per cent, of the mass. Moreover 

 the red beds when traced short distances become gray and 

 only the thicker strata seem disposed to hold their color. 



The proportion of sandstone beds to shale beds may be 

 called about 40 per cent. 



The sandstone beds vary in thickness from 2' to 10' and 

 are characteristically false or current-bedded. The lamina- 

 tion, as exhibited in the cliffs, is very curious. Each of 

 the horizontal beds are crossed obliquely by lines an inch 

 or two apart, weathered into furrows. The slope of the fur- 

 rows in one bed will be in one direction ; that of the beds 

 above and below in the opposite direction. The ends of the 

 furrows meet along the horizontal lines of stratification at 

 an acute angle. Consequently, when a considerable num- 

 ber of these sandstone beds, lying upon one another, are ex- 

 posed to view, the whole face of the cliff is sculptured in 

 zigzags from top to bottom. 



This false bedding sometimes shows regularly straight and 

 parallel lines ; at other times the lining is curved and the 

 laminae overlap each other at the bottom ; but at the top 

 they are cut off square. 



All geologists agree that this appearance can only be ex- 

 plained by supposing the sand to have been deposited in 

 strong currents of water ; that the direction of the currents 

 was continually changing ; and that when the current 

 changed it planed off the tops of the sand layers which had 

 been previously deposited.* 



*For a sketch of this kind of stratification in the neighboring counties of 

 New York, see Lardner Vanuxem's Report of 1844, Third district, New York 

 Geology, page 187. fig. 53. 



