Raymond: The Chazy Formatiox and its Fauna. 507 



( I. Dark -gray, massive limestone weathering in darker stripes 

 I an incli wide, containing the large Bncania seen elsewhere 



C. \ in this horizon. 40 feet. 



I 2. Tough silicious and magnesian rocks passing into a two-foot 

 1^ bed of pure sandstone. 17 feet. 



Total A, 15, C = 305 feet. 



Onocll, VcriHoiit. 



An exposure one mile northeast of Orwell village presents 59 feet of 

 dark gray strata lying between the Beekmantown and Black River 

 and containing Alachirites i/iatr;n/s, Orthoceras and Cyrtoceras. While 

 no basal sandstone can be seen at this locality, it is present on the 

 lake shore five or six miles to the northwest. 



The Canadian Extension of tJie Cliamplain l^a//ev. 

 Northeast of Chazy in the region of Fhillipsburgh, Canada, the Chazy 

 consists of slates, limestones, and limestone conglomerates (Ells), 

 while further north at St. Dominicjue it is again a limestone (Ells), and 

 at Montreal the formation consists mostly of a heavy-bedded limestone 

 with a little sandstone (Logan, Ami). No very good sections are 

 exposed in the region north of Lake Champlain, and the estimates of 

 thickness differ widely at the various localities, being as high as 2,000 

 feet around Standbridge and Bedford, according to Ells, and as low as 

 200 to 300 feet at Montreal, according to Ami. 



Si/inniaiy on Lake Cliamplain Region. 

 In this general region the formation consists mostly of an impure 

 limestone, frequently dolomitic, and the thickness decreases from 890 

 feet at Valcour Island to 60 feet at Orwell. From Ells' statements it 

 is probable that the thickness does not decrease north of the Canadian 

 line. At Montreal, Ami estimates the thickness of all the formations 

 from the Potsdam to the Lorraine, at only 1,275 feet, thus allowing 

 only 300 feet for the Chazy, and about the same for the lieekman- 

 town, but he states that a well boring reached the Potsdam at a dejjth 

 of 2,500 feet which, if the strata were horizontal, would allow 600 feet 

 for the Chazy and 1,200 for the Beekmantown. The writer is in- 

 clined to believe that Dr. .Vmi has greatly underestimated the thick- 

 ness of both these formations. ( See Transactions of tlie Royal Society 

 of Canada, volume 6, section 4, pages 125-164, 1900.) 



