EXTENT OF FOLDING AND SUBSEQUENT EROSION 



445 



of the anticlines had been 

 cut clown to the Bald Eagle 

 quartzites and conglomer- 

 ates. Here I think we have 

 the source of the Medina 

 red sands and of the suc- 

 ceeding Tuscarora white 

 quartzites, the Oneida con- 

 glomerate and its westward 

 extension, the T h o r o 1 d 

 quartzite or upper gray 

 band of Kochester, Niagara, 

 and the northwestern re- 

 gion. These relationships 

 are shown in figures 8 and 

 9. That a part of the beds 

 classed collectively as the 

 Juniata of Pennsylvania in- 

 clude some of the reworked 

 Juniata of Medina age can 

 not be questioned. It is this 

 uppermost part which con- 

 tains the Medina Scolithus 

 (8. verticalis) and in some 

 cases the Arthrophycus. 

 Whether the sea advanced 

 into Pennsylvania during 

 this redeposition of the old 

 Juniata sands and muds de- 

 rived from the folded region 

 of the cast is not certain. 

 Its existence in western New 

 York during part of the 

 time is proved. In any 

 case, whether continental or 

 partly marine, (he contact 

 of I he ,J uniata and Medina 

 would be obscured or ren- 

 dered wholly unrecogniz- 

 able, even though a congid- 



*<t 



