594 HISTORICAL GEOLOGY. 



ing to J. M. Clarke, (1) Marcellus sliale, 100' ; (2) a thin stratum of limestone of coral-reef 

 character, at the base of the Hamilton beds ; (3) the lower shales of the Hamilton, 140' ; 

 (4) the Encrinal Band ; (5) the Upper shales, 250'. In Chautauqua County, a boring gave 



50' Marcellus shale and 395' Hamilton (G. D. Harris, 

 893. 1891). To the eastward, the beds are coarser and 



more arenaceous. The TuUy limestone thins out 

 in the eastern part of Ontario County, and is the 

 most southern limestone in New York State. It 

 is quarried and burnt for lime in the village of 

 TuUy, Onondaga County, where it is 12' thick. 

 Section of HamUton beds, Lake Erie. Hall. The liagging-stoue of the Hamilton is quarried 



near Kingston, Saugerties, Coxsackie, and else- 

 where on the Hudson. In Perry County, central Pennsylvania, the Marcellus is 200' 

 thick, and the Hamilton, 900' or more ; they consist of shales and sandstones, and include 

 the Montebello sandstone. At the Falls of the Ohio, the Hamilton is represented by a 

 magnesian limestone, more or less shaly. On the west side of the Mississippi River, in 

 Iowa, outcrops south of Davenport consist of about 50' of shale with some crinoidal 

 limestone. In Missouri, Swallow reported the occurrence of Hamilton shales, 45' thick, 

 near Ashley, in Pike County. 



In eastern Pennsylvania, Monroe County, where the thickness of the beds of the Ham- 

 ton period is 1750' to 5000', that of the Marcellus shale is 200' to 800' or more. The shale 

 is black to gray in color, and the darker kinds are very carbonaceous, or even coaly at 

 times. Tully limestone is absent. The high cliffs on the Delaware, in Pike County, from 

 Port Jervis southward, are Hamilton. North-northwest of Monroe County, in Columbia 

 County, Penn., the whole thickness is 2200' to 2500' ; but farther south, near the south 

 border of Northumberland County, Penn., a highly disturbed region, the total thickness^ 

 for some reason, is stated to be only 600'. Prosser made a section across Monroe County, 

 along the D., L. and Western E.R., and found the Marcellus shale 800' thick, and the 

 Hamilton overlying it, 1400', the latter being proved by the fossils to include the Hamilton, 

 Tully, and Genesee beds of I. C. White's Report. 



In the Eastern-border region, at Gaspe, the 6000' of sandstones, above the 1100' 

 referred to the Corniferous period, are believed to be for the most part of Hamilton age. 

 St. John, in New Brunswick, is a noted locality of fossil plants of this era. In that 

 region there are (1) below, of the Middle Devonian series, the Dadoxylon sandstone 

 resting on the Bloomsbury conglomerate, and overlaid by the Cordaites shales ; (2) above 

 the Mispec conglomerate and slate ; and (3), of the Upper Devonian, the Perry sand- 

 stones, with remains of plants. (Dawson.) 



The Devonian is well developed in the Mackenzie River district, British America, and 

 southward in the vicinity of lakes Manitoba and Winnipegosis. In the Mackenzie River 

 district the section shows (1) at the base 200' of grayish limestone, interstratified with 

 dolomytes, the lower part of which may be older than the Devonian ; above this, (2) about 

 500' of greenish and bluish shales alternating with limestones, followed by (3) about SOC^ 

 of limestones. (McConnell.) 



Whiteaves has described a rich fauna, mainly from the upper part of the second 

 division. Among the species, 22 are also found in the Hamilton formation of Ontario 

 and New York ; 10 are also found in Iowa, there referred to Chemung ; and 7 are regarded 

 as characteristic Chemung fossils in New York and Pennsylvania ; 29 of the species are 

 either identical (19), or closely allied with European Devonian species. Mr. Whiteaves 

 considers the fauna to belong to the " Cuboides zone" of Europe, of which the Tully 

 limestone of New York is by Williams regarded as an equivalent. 



The Manitoba section consists of (1) a few feet of red shales resting upon Silurian 

 rocks, followed by (2) 200' of dolomytes, and then by (3) 50'-75' of calcareous shales, 

 above which are (4) the fossiliferous limestones containing the " Cuboides fauna." The 



