THE SHALES IN THE MOHAWK VALLEY. 



347 



graptolite beds lie the red roofing slates. At one locality 8 genera and 13 

 species of graptolites were found, all of which are identical with those found 

 at the Norman's kill locality.* The strata of the Hudson terrane cannot 

 be delimited clearly, as the base and summit of the series are not shown on 

 the east side of the river. I have estimated the upper division, composed 

 of cherts and shales, and green and red roofing slates, at 3,000 feet; and 

 the lower division, composed of calcareous sandstone and shale and dark 

 argillaceous shales, at 2,000 feet, which gives a total thickness of 5,000 feet 

 for the Hudson terrane on the east side of the river. 



In tracing the Hudson terrane westward in the valley of the Mohawk it 

 is found that the Utica shale and the lower slaty portion of the Lorraine 

 section occupy the entire section between the Trenton limestone and the 

 Oneida conglomerate. At Utica, the Utica shale is 710 feet in thickness* 

 and the entire upper portion of the Hudson terrane, consisting of shales and 

 sandstones in Albany and .Schoharie counties and of the same character of 

 rock in the Lorraine section, is represented by 90 feet of somewhat silicious 

 and, in places, sandy shale. At the section a little southeast of Utica, the 

 fauna is essentially that of the upper limit of the Utica zone in the Lorraine 

 section, and practically the same as the fauna discovered by Mr. Beecher 

 near Albany. The upper or true Lorraine fauna has not, to my knowledge, 

 been found to the eastward of this locality. At the city of Rome, fifteen or 

 sixteen miles west of Utica, the sandy beds become more frequent as inter- 

 bedded layers in the shale, and the fauna is larger and more like that of the 

 upper portion of the Lorraine section. f 



The explanation of the absence of this upper fauna in the beds beneath 

 the Lower Helderberg limestone, in the Hudson river valley section, 

 appears to be found in the area of non-deposition of the upper beds in the 

 vicinity of Utica. That the fauna is not present in the valley of the Hud- 



*Coenograptus f/racilis, Hall. 

 Didymograptus serratulus, Hal). 



" Sagittarius, Hall. 



Leptograptus subtenuis, Hall. 

 Dicellograptus divaricatus. Hall. 



" m.s, Hall. 



Dicranograptus ramosus, Hall. 



" furcatus, Hall. 



Climacograptus bicornis, Hall. 



pp. undt. (occurs at Nor- 

 man's Ki!l). 

 Diplograptus pristis, Hall. 



spinulosus. Ball. 



whitfieldi. Hall. 



Germs, 2, occurring also at Norman's Kill. 



fThe following species constitute the fauna found at Koine, New York 



I)* ndrograptus simpler, Walcott. 



Pala aster, sp. ? 



Heterocrinus heterodactyb's. Hall. 



h, oequalis, Hall. 

 Crania, n. s-p. 

 Pliolidops subtruncata, Hall. 



"inta, sp. 

 LepUrna sericea, Sowi rby. 

 Orthis testudinai ia, Dalman. 

 Am'- adiata. Hall. 



Modiolopsis modiolaris. Hall. 



" anodontoides, Hall. 



" curia. Hall. 



" faba. Hall. 



" cana llata, Walcott. 



Avicula iasueta, Conrad. 



Cleidophoi us planulaius, < lonrad. 

 Orthodesma parallelum, Hall. 

 Tellinomya levata. Hall. 



1/ i eh ■ 1 711 '"' I, Hall. 



■ at* lliformi8, Hall. 

 Bcllerophon bilobatus. Sow erby. 



" (cancetlata) texti Hall. 



Cyrtolites ornatus, Conrad. 



Plumulitt Hal I ami \\ hitfield. 



Acidaspu U mi . Hall. 



thrus bi '■'.". Green. 

 Asaphus finiiir, phi - ■■«. 

 fail/,:,, m calticephala, < Ireen. 

 , Katon. 



