286 THE CAMBRIAN. [BrLL.IL 



stone occurs in which the Olenellus or Lower Cambrian fauna is pres- 

 ent. The thickness of the strata referred to the Cambrian is not given 

 by Dr. Ells in his publication, but he told me that the measurements 

 given by Mr. L »gau were as nearly correct as could be determined. 

 These were 5,000 to 6.000 feet for the Sillery and Lanzon series. 



The little shell OboUUa pretiosa ranges through from 1,500 to 2,000 

 feet of the Upper Sillery : and the lower or Olenellus fauna conglomer- 

 ate occurs in the lower portion of this range. 



Dr. Ells i the entire Sillery series to the Cambrian, and in this 



I mainly agree with him. except that the upper portion is evidently a 

 formation betweeu the Cambrian and Silurian (Ordovician). 

 On iithologic and scintigraphic evidence the line would be drawn at the 

 summit of the red shale ; uu paleontologic evidence, as furnished by the 

 Graptolifces. I would include the upper portion of the Sillery red and 

 green shales in the Silurian (Ordovician), as I think they are above the 

 typical Potsdam zone of America. 



The strata doubtfully referred to the Cambrian group between Que. 

 bee and Cape I . on the south shore of the St. Lawrence River, have 



already been described in the notice of the work of Mr. James Richard- 

 son, reported upon by him in (Ante., pp. 118, 110.) As they 



may or may uot be of Cambrian age, no further description will be given. 



TL< i referred to the Cambrian on the western side of the Sut- 



ton Mountain anticlinal, or the belt extending southeasterly from Que- 

 bec to the Vermont boundary, are described by Drs. Selwyn and Ells 

 as consisting for the most part of hard quartzites interstratified with 

 micr Cfl and black slates. All of this series, as described by them 



is unconformably overlapped by the Sillery red slates, conglomerates, 

 and sandstones. Limited outcrops of grayish suVrystalline limestones 

 are found occasionally in association with the black slates and quartz- 



The volcanic portion of the Cambrian, or group No. 2 of Dr. Selwyn. 2 

 Hits a great variety of crystalline, subcrystalline, and altered r< 

 including • ■. thick-bedded, feldspathic, chloritic. epidotic, and 



quartzose sandstones, red. gray, and greenish siliceous slates and argil- 

 s of dioritic, epidotic and serpentinons breccias, and 

 g _ '.om era tes. diorites, dolorites. and amygdaloides, holding copper ore; 

 serpentines, felsites. and some fine-grained granitic and gueissic rocks, 

 also crystalline dolomites and calcites. Much of the division, especially 

 on the southeastern side of the a? locally made up of altered vol- 



canic prod; th iutrusive and interstratified, the latter being clearly 



of contemporaneous origin with the associated sandstones and slates/' 

 A^ m: u k: n this zone h afforded any fossils. Dr. Selwyn 



1 Walcott. C D. : A review of Dr. R. W. Ells's second report on the geolosy of a portion of the Pror- 

 in«-e of Quebec, with additional note-son the ''Qnebec group."* Am. Jour. r.. ToL39,189t, 



p 113. 



'Report of observations on the stratigraphy of the Qnebec gronp and the older crystalline rocks of 

 Canada. GooL Sorv. Canada : Report of progre .5 A, 6 A. 





