3ULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 19, pp. 155-176, PL. 11 • JULY7, 1908 



LOWEE POETION OF THE PALEOZOIC SECTTOX IX 

 NOETHWESTEEX NEW YOEK^ 



BT II. P. GUSHING 



{Read before the Society December 30, 1907) 



CONTENTS 



I'ase 

 lutroductiou 155 



The section 158 



lu general 158 



Potsdam sandstone 158 



Theresa dolomite 160 



Panielia limestone 161 



Lowville limestone 162 



Black River and Trenton limestones 1G3 



Historical 163 



Summary of the general section . . . . ; 165 



The Canadian section 166 



Sections along the Black river 167 



Age of the Theresa and Panielia formations 169 



Comparison with the Champlain and Mohawk sections 171 



Conclusion 175 



Introduction" 



During portions of the past two field seasons tlie writer has been en- 

 gaged in the areal mapping of the Theresa and Alexandria Bay quad- 

 rangles in northwestern New York (Jefferson county). While the main 

 problem was the investigation of the pre-Cambrian rocks, the importance 

 of a careful study of the Paleozoic series was fully appreciated, since this 

 is the region of the Frontenac axis, and since little work has been done 

 on these rocks since Emmons studied them, seventy years ago. 



Work was begun about Theresa, where the pre-Cambrian rocks and the 

 overlying Potsdam sandstone were studied and mapped. Above the 

 Potsdam a series of somewhat calcareous, sandv dolomites with inter- 



1 Published by permission of the State Geologist of New York. 

 Manusci-ipt received by the Secretai'y of the Society April 1, lOOS. , 



XVI— Bull. Geol. Soc. A.m., Vol. 19, 1907 (loo) 



