GEOLOGY OF OGDENSBURG 33 



beds between the Heuvelton sandstone and the Potsdam, the 30 feet 

 of divisions 3 and 4 being absent at Black lake, a break is suggested, 

 and probably will be demonstrated on further search. 







Fig. 2 Exposure in upper Theresa formation i^ miles southeast of Morris- 

 town, showing the sandstones and calcareous sandstones cut out 

 by a coarse conglomerate. Only one side of this channel-filling 

 can be seen, as the exposure gives out to the east, only a small 

 portion of the original mass of the conglomerate showing. 



The fossils. As has been stated, not only the Heuvelton sand- 

 stone, but also the beds both above and beneath contain large but 

 poorly preserved gastropods sparingly. So far as our evidence 

 goes, the same fauna runs through all of them. We are much 

 indebted to Dr E. O. Ulrich for the examination of these fossils, 

 upon which he reports as follows : 



" The fossils in zones 1-3 (the Heuvelton sandstone and the 

 beds just beneath and above) though poor, indicate at least three, 

 and possibly five species of gastropods: (i) a fragment of a 

 Sinuopealike shell suggesting nothing else so much as a new species 

 of Sinuopea from the Upper Ozarkian, Chepultepec dolomite of 

 east Tennessee. Nothing like it is known to me from "the Lower and 

 Middle Ozarkian; (2) a narrow, whorled gastropod belonging to 

 a new genus allied to Liospira. This species resembles the 

 ''Pleurotomaria hunterensis" but has a flatter top. 

 A more similar, possibly identical, shell, occurs in the Chepultepec, 

 and in the corresponding Gasconade and Oneota formations, 

 respectively of Tennessee, Missouri, and Minnesota-Wisconsin; 

 (3) a second Liospiralike shell, closely simulating a Chepultepec- 

 Gasconade fossil. It also recalls a species of the Beekmantown and 

 Cotter (both Canadian, the latter a new Arkansas-Missouri forma- 

 tion) ; (4-5) two other, both wider- whorled, Liospiralike shells 

 are indicated. Both may be compared with Gasconade species, but 

 similar types also occur in the Canadian and Ordovlcian." 



