358 THE CAMBRIAN. [bull. 81. 



tive stratigraphie succession of the sub-divisions of the Upper Cam- 

 briau fauna is the same; and nowhere do we know of the existence of 

 formations characterized by the Lower and Middle Cambrian faunas 

 of the Atlantic coast, Appalachian and Rocky Mountain provinces, 

 except, perhaps, the Middle Cambrian fauna in the southwestern Interior 

 Continental sub-Province. 



In the Atlantic Coast Province the basal beds of the Olenellus zone 

 rest unconformably upon Archean and Algoukian rocks. The sea de- 

 posited the Cambrian sediments across the upturned edges of theLau- 



rentian and those of the superjacent 

 $ v bedded sandstones, quartzites, argil- 



| -g 1 lites, and slates forming the Algon- 



ue. -mLb 3 kian series, which Dr. Murray referred 



M.C? 



u.c 

 Ar 



to the Huronian. The upper St. ' 

 27~ 28 " 2i "" John's slates carrying the Aspidella 



Fig. 5.— Sections of the Interior Continental Were also plaued away by the Cam- 

 Province, in the sonth central and south- ^rian Sea. In the Interior Continental 



western portions. _ . . -^ . . _ _ ,. 



Province in Wisconsin and Minnesota 

 the Upper Cambrian sandstones are unconformably superjacent to the 

 corresponding series of rocks, or the Laurentian, Huronian, and 

 Keweenawan series of the Lake Superior region. In the first instance 

 the earlier Cambrian sea transgressed upon the pre-Cambrian rocks, and 

 in the latter case the later or closing epoch of the Cambrian was the 

 one in which the deposits were accumulated upon the Archean and 

 Algonkian rocks. A misapprehension of these facts has led several 

 geologists to refer the Keweenawan and other pre-Cambrian rocks to 

 the Cambrian. 



DESCRIPTION OF PLATE I. 



Geographic distribution of the Cambrian strata shown by surface outcrops in North 



America. 



The geologic provinces are indicated by the dotted lines. The Interior Continental 

 Province is broken up into sub-provinces and these are united by a lighter dotted 

 line. The provinces are : 



A. — Atlantic or Eastern Border Province. 



a. Eastern or Nova Scotia Basin. 



b. Southeastern Newfoundland, eastern New Brunswick, and Massachu- 



setts Basin. 



c. Interior deposits of Gasp6, Quebec, Maine, New Hampshire, Vermont, 



and Massachusetts. 

 B. — Appalachian or Interior Eastern Border Province. 

 C. — Rocky Mountain or Western Border Province. 

 D. — Interior Continental Province. 



D l . Central Interior or Upper Mississippi and Missouri. 

 D 2 . Eastern Interior or Adirondack of New York, and Canada. 

 D 3 . Western Interior or Dakota, Wyoming, etc. 

 D 4 . Southwestern Interior or Arizona and Texas. 

 The outlines of the x>rovinces are drawn so as to include the outcrops known at 

 present. They are arbitrarily assumed, as we do not know the exact limits of the 

 original Cambrian sedimentation. 



