118 THE CAMBRIAN. Ikull.81. 



red and green shales with thin layers of gray sandstone or qnartzite in 

 which Lingula and Obolella were found. At the summit of the red and 

 green shales, interstratified sandstones appear and succeed the shales, 

 with a thickness of about 2,000 feet, forming the Sillery division of the 

 Quebec group (p. 232). Subsequently he 1 divided the Quebec group 

 into three parts : Levis or lower; Lauzon or middle ; and Sillery or up- 

 per. The Lauzon or middle division embraces the red, green, and pur- 

 ple slates of the section above and below Quebec and on the island of 

 Orleans. The only fossils known were Obolella pretiosa and fragments 

 of Lingula. The sandstones and accompanying shales of the original 

 Sillery were referred to the Sillery or upper division with the exception 

 of those separated to form the Lauzon. The Levis, or lower division, 

 was distinguished by its yellow, dark and black shales and the presence 

 of numerous graptolites and Calciferous-Chazy fossils. 



Up to this time none of the rocks of the Quebec group had been 

 referred to the Cambrian system, or to an equivalent formation, beneath 

 the Caleif'crous zone of the New York series. Messrs. Billings, Hall, 

 and Barraude spoke of the Primordial character of some of the fossils 

 of the Point Levis conglomerate, but the series as a whole was referred 

 by Mr. Logan to the Calciferous-Chazy zone. 



Sir W. E. Logan also described the conglomerate beds of Bic Har- 

 bor and Trois Pistoles on the shore of the St. Lawrence River, where 

 bowlders of limestone were found containing fossils of the Olenellus 

 fauna. 2 The shales in which the bowlders occur are supposed at the* 

 present time to be of Upper Cambrian age. 



The report on the south shore of the St. Lawrence River below Que- 

 bec, by Mr. James Richardson, contains the information that another 

 series of rocks came to the surface, differing from those farther to the 

 west. He says : 



These rocks have heretofore been classed with those of the Quebec group, but they 

 appear to underlie them uncouformably, and being in some places marked by fossils 

 which Mr. Billings considers to be of Potsdam age, they are now placed in the upper 

 part of the Potsdam group. 3 



They consist at the summit of a light drab quartz rock with intercal- 

 ated beds of conglomerate holding limestone pebbles in an arenaceous 

 matrix, the whole forming a series GOO feet in thickness. This is super- 

 jacent to a series of gray saudstones and interstratified shales with a 

 thickness of 700 feet iu which near the base a conglomerate occurs j 

 below this a third division of gray limestones and limestone conglom- 

 erate occurs in beds of from 1 to 6 inches thick. A species of Salter- 

 ella was observed in the limestone, and a species of Arcbreocyathus in 

 the shales. The third series is assigned a thickness of 700 feet ; and the 



1 Logan, W. E., Report of, for 1866. Geol. Survey Canada, report of progress from 1863 to 1866, 1886, 

 p. 4. 



2 Geological Survey of Canada, report of progress from its commencement to 1863. Montreal, 1863, 

 p. 260. 



3 Report on the south shore of the St. Lawrence, helow Quebec. Geol. Survey Canada, report prog- 

 ress for 1866, to 1869, 1870, p. 120. 



