134 INDEX TO THE STRATIGEAPHY OF NORTH AMERICA. 



Dr. Ells refers the Sillery series to the Cambrian and in this I mainly agree with him, 

 except that the upper portion is evidently a passage series between the Cambrian and Ordo- 

 •vician. On lithologic and stratigfaphic evidence the line would be drawn at the summit of 

 the red shales. On paleontologic evidence, as furnished by the graptolites, I would include 

 the upper portion of the Sillery red and green beds in the Ordovician, as I think they are above 

 the typical Potsdam zone of America. 



It will be recalled that Dr. Ells stated that the Sillery beds rested unconformably upon 

 the slates, quartzites, etc., which he refers to the Lower Cambrian. He mentions that, in this 

 lower series, beds of gray subcrystalline limestone occur. It may be that we here have the 

 source from which the hmestone conglomerate of the Sillery was derived, which contains the 

 Olenellus fauna. This would be in accordance with the mode of occurrence of the Olenellus 

 or Lower Cambrian fauna to the southward, in Vermont and eastern New York. 



In this quotation Walcott states that he would refer the Cape Rosier beds to 

 the " Calcif erous " (Beekmantown) rather than to the Upper Cambrian as was done 

 by Lapworth and Ells.''-'"" 



The Umestones near PhiUipsburg, which in the preceding quotation are assigned 

 to the " Calcif erous " (Beekmantown), were thus described by Logan r^*^'' 



A. 



Feet. 



1. Dark-gray and yellowish-white dolomites, weathering gray and yellowish brown 400 



2. White and dove-gray pure compact limestones 100 



3. Reddish-gray, brown-weathering dolomites and black dolomites with some thin-bedded 



black 'limestones ; 200 



700 

 B. ~ 



1. White and dove-gray pure limestones, with some yellow-weathering magnesian bands 120 



2. Dark-gray and black limestones, some of the beds magnesian 120 



3. Dark bluish-gray thin-bedded nodular limestones, with thin layers of bluish-gray slate; 



probably magnesian; the surfaces of some of the beds weathering into a red or yellow 

 ocherous arenaceous earth 150 



4. Black slaty thin-bedded nodular limestones, with two or three thick beds of purer lime- 



stone toward the base. 300 



5. Black limestones, some of them massive, weathering bluish gray; interstratified toward the 



bottom with black and dark-gray, yellow- weathering magnesian beds 350 



1,040 



The remainder of this section comprising divisions C and D is given on pages 

 845-846 of Logan's report. 



The faunas of the Potsdam and " Calcif erous " of the Eastern Townships of 

 Quebec and of the Phillipsburg formation are listed by Ami.^*'' 



li 19. MAINE. 



Certain shaly, calcareous, and quartzitic strata, which are highly altered, 

 occur on the shores and islands of Penobscot Bay, where they have been studied 

 in detail and provisionally assigned to the Cambrian by Smith, Bastin, and 

 Brown,^®"^ who say : 



The oldest rock of the Penobscot Bay region is the Ellsworth schist, wliich represents 

 sediments probably of Cambrian or even pre-Cambrian age. The deposition of these arena- 

 ceous sediments was followed by dynamic action sufficient at least to inaugurate the changes 

 of impure sand into a crystalline schist. This metamorphism is beUeved to have begun before 

 the deposition of the next younger formation, inasmuch as the Ellsworth schist exhibits a 

 much greater degree of alteration than any other rock in the quadrangle. 



