ETCHING OF QUARTZ IN CONGLOMERATES 



8l 7 



mass of the rock. The portions of the conglomerate bowlders 

 lying in the humus or exposed to the atmosphere, though some- 

 times presenting roughened surfaces suggesting etching, proved 



B. C. 



Fig. 2. 

 A. Etched surface of a bedding plane in Pottsville conglomerate from Blossburg, 

 Tioga county, Pa. 



B and C. Etched surfaces from opposite sides of bedding plane in a sandy 

 portion of Pottsville conglomerate from Blossburg, Tioga county, Pa. 



on examination to be unetched, the roughening being due to the 

 separation of entire grains by the ordinary processes of disinte- 

 gration. The deep channels and pot-like cavities observed in 



