GENERAL OBSERVx\TIONS. 19 



fill to the Tertiary period. In vie-^v of the fact, however, that strata at some 

 localities in that Territoiy, containing a fauna as suggestive of the Tertiary 

 period as these fossils are, have been found to underlie strata containing 

 true Cretaceous types, I prefer at present to regard the reference of at least 

 the greater part of them to the Tertiary period as provisional. 



Note.— After writing the foregoiug, I learued tliat my friend, Mr. E. P. Whitlield, the well-known 

 paleontologist, had been making some special studies of tbe Graptolite slates of Norman's Kill, and 

 wrote to ask bis opinion npon tbo subject, to wbicb iuquirj' I have received tbe following reply. I 

 insert it here because of its important bearing uiJon tbe question of tbo age of tbe shales at Bel- 

 mont, Nev. : — 



"Albany, N. Y., February 18, 1875. 



"Dear Sir: Your inquiry in regard to the geological age of tbe Graptolite slates of Norman's Kill 

 near Albany, N. Y., involves a question of considerable complexity, and is one to which I have given 

 much thought and labor during several years past. Tbe rocks in that vicinity are so altered and dis- 

 turbed that their relative position is not easily determined from stratigraphical evidence. I have sought 

 diligently at all points for fossil remains, but with only limited success thus far, except as to Graptolites. 

 From the evidence furnished by these fossils, I have reached tbe conclusion that the Graptolite-bearing 

 layers there are of the age of tbe Utica slate, tbe following being a summary of the facts I have observed : — 



"I have found the following species common to both the Graptolite layers at Norman's Kill and 

 those of the Utica slate formation at the mouth of Oxtungo Creek near Fort Plain, N. Y. : — GraptoUtUus 

 (Monograptus) seiratulus Hall; G. {Dlplograptus) pristis Hall (not Hisiuger) ; &. {Climacograptus) bicorvis 

 Hall; and G. {Dicranograptun) ramosus Hall. 



"At Ballston, N. Y., G. hicornis Hall is very abundant in the Utica slate ; and at Barker's Falls, near 

 Sandy Hill, N. Y., G. pristis is equally abundant in the same formation. On the island of Orleans in the 

 Saint Lawrence River, and in tbe valley of the SainfrAnne River in Canada, three of tbe forenamed 

 species are known to occur, viz, G. pristis, G. ramosus, and G. hicornis Hall, in beds known to be of the age . 

 of the Utica slate (see Geological Report of Canada, 1863, page 200). I think that G. (Dicranograptus) 

 Sextans Hall also occurs in tbo same layers with the above-mentioned specie's, but I will not be positive, 



"I am coufident that if all these localities were as thoroughly examined as that at Norman's Kill 

 has been, many more species would be found to be common to two or more of them ; but the evidence 

 already given is quite sufficient to warrant the conclusion that the slates of the several localities named 

 . are of the same geological age, especially wheu we consider the fact that Graptolites have a very limited 

 geological range. Although only four species are positively known to be common to two or more of the 

 localities named, some of them are found at widely-separated characteristic localities of tbo Utica slate, 

 ■which shows the great geographical range of the species. None of the Norman's Kill species have been 

 recognized in any other formation than the Utica slate, which, while it demonstrates their equivalency 

 of geological age, also shows the limited geological range of this family of fossils. 



"Besides the foregoing evidence, the following facts are worthy of consideration in this connec- 

 tion. The lithological features of tbe Norman's Kill Graptolite beds are peculiar, quite different from the 

 other beds near by, easily recognized at distant localities, and evidently as near like tbe Utica slate as a 

 metaniorpbic slate can belike an unaltered one. At a locality of these slates ne.arCohoes, I found specimens 

 of G. pristis undistinguisbable from Norman's Kill specimens, and in another layer not many feet from the 

 first, but of sonie%vbat different lithological characters, I collected Orthis testudivaria, Leptwiia scricea, 

 Bellcrophon hilobatus, aud Trinucleus concentriciis, also an Orthoccras and several small lamellibranchiate 

 shells. In another layer, a short distance from the first and in a direction opposite the second, but 

 nearly in the strike of the beds, I found specimens of an Orthis closely like, if not identical with, 0. 

 subqnadraia Hall. On tbo opposite side of tbe Hudson River, near the base of tbe hills just above 

 and back from Lansiiigburgh, a mile or more from the river, I obtained G, pristis and G. fiircatiis, 

 another Norman's Kill species. Just south of Troy, iu the shaly partings between layers of metaniorpbic 

 limestone, I have found a species of Graptolite in great abundance uudistiugnisbable from <t. amplixicaule 

 Hall, from the Trenton limestone of Herkimer County, New York. The same species was also found 

 abundantly in tbo yard of the arsenal at Watervliet by Capt. C. E. Button, U. S. A. At Norman's Kill, 



