112 a D. Walcott— Review of Dr. R. W. Ells' s Report 



the lower zone, and we found traces of extensive collecting. 

 With this exact data I was enabled, at once, to correlate the 

 lower belt of limestone and conglomerate with the central band 

 of the Phillipsburgh section, where an identical fauna occurs 

 1000 to 1110 feet above the recognized Potsdam sandstone.* 



This zone is 600 feet beneath the zone of u Maclurea pon- 

 derosa" where Mr. Billings placed the Levis conglomerates. 

 The long period of uncertainty regarding the true mode of 

 occurrence of the faunas in the Levis calcareous rocks is now 

 terminated, and a fixed datum point secured for comparison 

 with the known section on the shores of Lake Charaplain. 



Dr. Ells quotes the greater part of the conclusions contained 

 in Professor Charles Lapworth's instructive paper on the 

 graptolites of the " Quebec Group, "f In this the graptolitic 

 zone of the Levis shales is correlated with the typical Arenig 

 of Great Britain and the Phyllograptus beds of Scandinavia. 

 The graptolites of the Citadel Hill or Quebec City strata are 

 correlated with the middle Llandeilo zone of Great Britain. 



The stratigraphic succession, as determined by Dr. Ells, is as 

 follows (p. 61K) : 



1. Black, green and gray shales, with thick bands of grayish 

 and sometimes yellowish-white quartzose sandstone and occasional 

 thin bauds of limestone conglomerate. 



2. Greenish, grayish and blackish, and occasional bands of 

 reddish or purple shales, with thin layers of gray sandstone. 

 Annelid trails (fucoidal markings of Ells) are numerous on the 

 greenish shales. On the south shore of the St. Lawrence, below 

 Levis and also on the south shore of the Island of Orleans, beds 

 of conglomerate occur at about this horizon, in which the Lower 

 Cambrian fauna occurs (p. 65K). 



3. Bright-red shales, with thin bands of greenish and gray 

 shale. 



4. Red, greenish-gray and black shales, with interstratified 

 Sillery sandstones. 



Obolella pretiosa in the upper part, near Sillery, and on the 

 south side of the river, Obolella pretiosa, Protospotigia fenes- 

 trata, Phyllograptus typus, Tetragraptus serra and Lingula 

 quebecensis. 



5. Levis shales and conglomerates of Point Levis. 



6. Black and grayish-striped or banded shales, with the Jblack 

 and graphitic shales and limestone of the Arthabaska and Som- 

 erset synclinal, the latter not appearing in the Quebec and Point 

 Levis sections. 



V. The black or brownish bituminous shales and limestones of 



* During the summer of 1888 I discovered the Potsdam sandstone beneath the 

 limestones of the Phillipsburgh terrane, on the shore of Missisqucis Bay, one mile 

 south of the wharf at Phillipsburgh. The section was measured from this hori- 

 zon to the Chazy-fauna zone, and then to the Trenton limestone. 



f Trans. Roy. Soc. Canada, 1886, section iv, pp. 167-184. 



