II P. Gushing — Lower Paleozoic Rocks of New York. 135 



Akt. XVIII. — Nomenclature of the Lower Paleozoic Rocks of 

 New York ; by H. P. Gushing.* 



Introduction. — Work on the early Paleozoic rocks of north- 

 ern New York during the past few years has not only added, 

 materially to onr knowledge concerning them, but has empha- 

 sized the necessity of certain modifications and certain ampli- 

 fications of the nomenclature. Since these results are scattered 

 through various official publications, it is believed that a sum- 

 mary of them will be a convenience to many. 



Though begun by Cushing, the work has been actively par- 

 ticipated in by Drs. Ulrich and Ruedeinann. We have been 

 so closely associated, and have so freely shared ideas, both in 

 the field and in correspondence, that it is now an utter impos- 

 sibility to assign to each his appropriate share. The writer 

 therefore appears here merely as the scribe, and not at all as 

 the sole author. 



The Saratogan Formations. 



Ulrich and Cushing have, in a recent paper, presented the 

 detailed evidence which has led to the belief that the Little 

 Falls dolomite, formerly classed with the Beekmantown, belongs 

 rather in the same group with the Potsdam sandstone. It is 

 not the intention to repeat the discussion here, but merely, for 

 the sake of completeness, to note the matter, f The Saratogan 

 in New York consists of the Potsdam sandstone below and 

 Little Falls dolomite above, with a series of passage beds be- 

 tween named the Theresa formation. The Little Falls dolo- 

 mite is shown to be the equivalent of the basal division and a 

 half of what was formerly classed as Beekmantown in the 

 Cham plain valley. It comprises division A and the lower 

 half of division B. In the Mohawk valley the Potsdam dis- 

 appears because of overlap and the Little Falls rests on the 

 Precambrian. In the Black river valley both disappear and 

 still younger beds lie on the Precambrian. 



The fossiliferous limestone which overlies the Potsdam at 

 Saratoga and which furnished the fauna described by Walcott 

 and determined by him to be upper Cambrian, was named the 

 Greenfield limestone by Clarke and Schuchert4 This name 

 was preoccupied, having been applied by Grabau to an Ohio 

 formation of Monroe age. We propose to call it the Hoyt 

 limestone, and we regard it as a local, calcareous phase of the 

 basal portion of the Little Falls dolomite, of which it becomes 

 a member. It is exceedingly local, being confined, so far as 



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

 fBull. 140, N. Y. S. M., pp. 97-140. X Science, Dec. 15, 1899. 



