274 



THE CAMBRIAN. 



[bull. 81. 



It is the record of the accumulation of sediments in a gradually deep- 

 ening sea. 



The eastern Massachusetts section is largely formed of shale, except 

 in the lower part, where a small proportion of limestone occurs in the 

 Olencllus zone, much as in the southeastern Newfoundland section. 



The great thickness of shales referred to the Cambrian in Nova 

 Scotia, Maine, and New Hampshire probably represents much more 

 than the Cambrian group, or it may be entirely a pre-Cambrian forma- 

 tion or a post-Cambrian formation. It is only probable that tbey are of 

 Cambrian age. They may represent deep-water accumulations in which 

 no organic remains were buried. 



As a whole, we may regard the Atlantic Coast Province, during Cam- 

 brian time, as including bays and the adjacent shores of the Algonkian 

 land, in and along which sediments, mostly of an argillaceous and 

 arenaceous character, accumulated. The relative level of the sea bed 

 varied, but in the main the depression greatly exceeded the elevation. 

 The depth of water in which the sediments forming the limestones and 

 shales accumulated was probably considerable, but not a deep sea in 

 the present sense of the term. A few hundred or a thousand feet on a 

 gradually sinking sea bed (in relation to the coast line) would give the 

 required conditions. From the character of the sediments and tbe 

 faunas it is probable that laud barriers existed to the eastward of the 

 present coast, and that none of the deposits were accumulated oft" the 

 shore facing the open ocean. 

 As left by erosion the Lower Cambrian now occurs on the Labrador 



coast, on the western and eastern sides 

 of Newfoundland, in New Brunswick, 

 and eastern Massachusetts. The Mid- 

 dle Cambrian has been recognized on 

 the eastern coast of Newfoundland, in 

 New Brunswick, and eastern Massa- 

 chusetts. The Upper Cambrian is 

 known in southeastern Newfoundland, 

 Cape Breton Island, New Brunswick 

 and doubtfully on the southwestern 

 coast of Newfoundland. (See PI. u.) 



M.C. *•. 



LC 



Fir.. 1. — Typical nections of the Atlantic 

 Coast Province. Vertical scale, 6,400 feet 

 to the inch. 



APPALACHIAN PROVINCE. 



The Appalachian Province includes the outcrops of Cambrian strata 

 on the line of the Appalachian System of Mountains, from the Gulf of 

 St. Lawrence on the north to Georgia and Alabama on the south. 



For convenience in presenting geologic data the Ax>palachian Prov- 

 ince is divided into : 



A. — Northern Appalachian District. 

 B. — Southern Appalachian District. 



