184 



Report of the State Geologist. 



side of this hill; and if this exposure at the creek be at about the top of the 

 Hamilton, we would have a dip of fifty feet per mile to the south. 



XIX O 2 . About sixty-three feet above the Hamilton shales at the fork 

 of Nigger brook, on its south branch on the Ertz farm, are blackish shales. 

 This locality is hardly one mile above the Lee quarry, and barometrically 108 

 feet higher. The rocks which are well exposed along the bed and side of the 

 brook are even-layered argillaceous shales, part of which are decidedly blackish 

 in color. The shales contain a few fossils, the following species having been 

 < »1 itained : 



1. Glyptoca/rdia speciosa, Hall. (r) 



2. Leptodesma Roger*!, Hall. (r) 



3. Coleolus acundi/?)!., Hall (?). (c) 



Slender tapering specimens without surface markings, and very 

 near the figures of this species. 



4. Orthoeeras cf. mbulaPum, Hall (?). (r) 



5. Goniatites cf. disco/deux, Hall. (c) 



Very imperfectly preserved. 



These shales are considered to belong in the Sherburne formation, and in 

 lithologic characters are quite similar to the darker shales of the Portage for- 

 mation in western New York. 



XIX O 3 . Along the south branch of Nigger brook are but few outcrops 

 of any importance after passing the black shales of the Ertz farm. However, 

 at the head of the vallev, two and eiirht-tenths miles east of the river road and 

 378 feet above the black shales of C 2 , is a led ire of thin shaly sandstones on the 

 Gr. S. Sherdin farm. These shaly sandstones form a ledge on the south side of 

 the highway and contain a considerable number of fossils. Spvrifer mesastrialis, 

 Hall, is common, several specimens preserving the external surface of the shell 

 and showing clearlv the markings of the fine striae w hich characterize this 

 species. Two specimens are very broad, like that shown in figure IS, plate XL. 

 Vol. IV of the Palaeontology of New York, and there can be no doubt as to 

 the correctness of the identification «>f this species. Professor Clarke has 

 suggested that the appearance of the above species is evidence of a change 

 from the Hamilton t<> the Ithaca formation. 1 I would also state that this 

 species is generally above the first species of this fauna, and is not present 

 until the Ithaca fauna is fairly well represented. A search of twenty minutes 

 in these thin sandstones furnished the following: 



I Thirteenth Animal Report State Geologist [Now York], p. 55-4. 



