106 C. D. Waleott— Review of Dr. R. W. Ells' s Report 



Mr. Billings's study of the fossils collected from the Point 

 Levis beds proved that the rocks at Point Levis were far below 

 the Hudson River group, and Pre-Trenton in age. These 

 conclusions were first announced by Logan in 1860, and, sub- 

 sequently, in March, 1861, when the opinion was expressed 

 that " this series of rocks, to which the name ' Quebec Group r 

 is now applied for the first time, represents a great develop- 

 ment of strata about tne horizon of the Chazy and Calcifer- 

 ous." With the paleontologic proof of the age of the rocks 

 the history of the " Quebec Group" assumed a new aspect. 

 The five divisions of the grauwacke series of 1849 were divided 

 into two portions, the first four of which were united to form 

 the "Levis" formation, while the last was called the "Sillery."' 

 The former was subdivided into seventeen parts, having a total 

 supposed thickness of 5,025 feet, at the summit of which was 

 placed the series of greenish sandstones and red and green 

 shales of the " Sillery," which was given a total thickness of 

 2,000 feet. 



In the Geology of Canada, for 1863, pp. 225-297, Logan 

 gives with great detail his views of the structure and strati- 

 graphical position of the several rock formations, which he re- 

 ferred to the " Quebec Group." The group was then divided 

 into the "Levis" and "Sillery" formations, and referred to 

 about the age of the Chazy and Calciferous formations. (GeoL 

 Canada, 1863, p. 233.) 



Subsequently (Rep. Prog. 1866, p. 4) Logan divided the 

 "Quebec Group" into three parts — the "Levis" or lower, 

 " Lauzon " or middle, and " Sillery " or upper. 



The "Levis" or lower division was distinguished by its 

 general dark and black color and the presence of numerous 

 graptolites and Calciferous- Chazy fossils. The "Lauzon" or 

 middle division embraced the red, green and purple shales of 

 the section above and below Quebec and on the Island of 

 Orleans. The only fossils known were Obolella pretiosa and 

 fragments of Lingula. To the "Sillery" or upper division he 

 referred the sandstones and accompanying shales of the original 

 Sillery, with the exception of those separated to form the 

 Lauzon. The strata were unfossiliferous, as far as known. 

 The dark shales, upon which the city of Quebec is built, were 

 referred to the 'Levis" and the series of strata referred to 

 the "Levis," "Lauzon" and "Sillery" formed the typical 

 " Quebec Group," in the vicinity of the city of Quebec. 



As far back as 1848, Logan held the view that the metamor- 

 phic rocks of the eastern townships of Quebec, or the rocks of 

 the Green Mountains of Vermont, in their prolongation into 

 Canada, were altered Hudson River Group strata, with the 

 possible addition of the Shawangunk conglomerates. 



