158 H. r. GUSHING PALEOZOIC IN NOETHWESTEKN NEW YORK 



toAvnshii> of that name, in -n'hich it is exposed in its entirety'. For 

 reasons of similar nature, tlie name "Pamelia" was ajjplied to the upper 

 formation as a provisional name for mapping purposes, to serve until 

 time should show whether a specific designation was or wns not needful 

 for the formation. 



The above results were commimicated to Ulrich and Ruedeuiuan on 

 their arrival and the fossils were shown them, following which two daj^s 

 were spent in going over the section together, with further considerable 

 collection of fossils. Their expressed conclusions were confirmative of 

 the views above expressed as' to the close relationship of the Theresa and 

 Potsdam, the absence of the normal Beekmantown, and the probable 

 Stones Eiver age of the Pamelia limestone, it thus representing a forma- 

 tion heretofore unrecognized in the ISTew York section.^ 



The Section » 



in general 



A generalized section of the rocks from the pre-Cambrian up to and 

 including the lower 50 feet of the Trenton is given in the accompanjang 

 figure, with the two unconformities also indicated. The figure also 

 brings out the fact that two -overlaps occur in the section, and that the 

 Potsdam overlap came from the east and was on a surface which sloped 

 in that direction, while the Pamelia overlap came from the opposite 

 direction, or, more strictly, from the southwest, and that hence the 

 former represents the westerl}' edge of a deposit in an eastern, and the 

 latter the easterly edge of a deposit in a western basin. 



POTSDAM SANDSTONE 



This is the basal paleozoic member of the region and rests upon the 

 eroded surface of the pre-Cambrian rocks. "While this surface is dis- 

 tinctlv and often abruptly uneven, being a ridge and valley surface, the 

 irregularities have no great vertical extent, none noted exceeding 75 feet, 

 while the majority do not exceed 50 feet; but the thickness of the forma- 

 tion has not been found to be greater tlian 80 feet an}Tvhere within the 

 limits of the two quadrangles, and the general formation thins both west- 



= Thls informal and somewhat lengthy introduction seems not inappropriate, even 

 though unusual, since it serves in the first place to indicate the fortunate combination 

 of circumstances under which the work was done, and in the second place to set forth 

 the part played by each of us in connection with the work, the participation of Ruede- 

 mann and Ulrich really amounting to actual collaboration. Especially serviceable was 

 Ulrich's intimate acquaintance with rocks of similar age over a wide extent of territory, 

 giving great value to conclusions which are backed by his approval. 



