682 



Report of the State Geologist. 



In a ledge a short distance southeast of the Moshier quarry is an 

 exposure of ten and one half feet of Birdseye limestone. From this ledge and 

 the upper part of the Moshier quarry the following species were collected : 



1. Pln/topxix tubulosa, Hall. (c) 



Small specimens similar to figures 1, lc, PI. 8, Pal. N. Y., Vol. I. 



2. Murchisonia cf. varicosa, Hall. (r) 



3. Orthoeeras midticameratum, Con. (c) 



4. Modiolopsis sp. (r) 



5. Rajmesquma alternate (Con.), Hall and Clarke. (c) 



6. Leperditia sp. 



A specimen from the upper part of the Birdseye limestone at this 

 locality was analyzed by Mr. McKeefe, with the following result : 



SiO a 4.50 per cent. 



Fe,0 3 2.04 



CaC0 3 92.7(5 " 



MgC0 3 1.65 " 



100.95 per cent. 



All of the limestone shown in the lower part of the Moshier quarry is 

 considered as belonging in the Birdseye, which gives the subformation at this 

 locality a thickness of at least twenty-two and three-quarters feet. Emmons 

 stated that the thickness of the Birdseye to the northwest in Jefferson 

 county, was "not far from thirty feet."* 



Little Falls. 



Thirteen miles southeast of Newport in the Mohawk valley, is Little 

 Falls, a locality famous alike for its natural scenery and geologic structure. 

 The section is introduced here in order to give the thickness of the Calcif- 

 erous sandrock and to show the decrease in thickness of the Trenton 

 limestone as compared with that at Trenton Falls, only twenty-two miles 

 to the northwest. At this place is the upper gorge of the Mohawk river, 

 where the falls and the lower part of the cliffs are composed principally of 

 gneiss, which lias generally been referred to the Laurentian system of the 

 Archaean. The gneiss is excellently exposed in the cliffs on the northern 

 side of the river along the tracks of the New York Central railroad, in the 

 eastern part of the city, as may be seen in Plate VI. Above the gneiss are 

 steep walls of Calciferous sandrock w hich are especially conspicuous on the 

 southern side of the river opposite the railway stations. 



• Geology of New York, Part II, 1842, |). 385. 



