38 JOURNAL O^ THE 



lie now upon its edges where they were deposited, the 

 later sediments of the stratified series. 



Havino- found out something" of the position of the 

 land of the Atlantic coast region at the initiation of the 

 Cambrian period, we may begin to formulate our 

 knowledge of the shore-line history from that date. 



First let us observe that the evidence of former shore- 

 lines given by actual marks of the shore itself is of 

 such a transitory nature that we must not expect to 

 find such evidence in the older rocks. While they may 

 retain a perfectly characteristic form through the 

 Quaternary period or even long-er, the chances of their 

 preservation from earlier times becomes less and less as 

 w^e go back into the geological past. In the Cambrian 

 then we are forced to reason almost entirely from the 

 nature of the sediments, that is, their texture, and com- 

 position, and their position with respect to the source 

 of the materials forming them. 



There are very few undoubted Cambrian rocks in 

 North America w^hich can with any degree of certainty 

 be ascribed to the Atlantic field of deposition. In the 

 Cambrian Correlation Papers of C. D. Walcott, a series 

 of rocks of Cambrian age, including slates, quart^ites, 

 conglomerates and limestones, are located and briefly 

 ■described under the general name of the Atlantic coast 

 province. These areas are rather small and discontin- 

 uous, and extend in a general southwesterly^ direction 

 from the southern coast of Labrador, across Newfound- 

 land, Nova Scotia, and ending in eastern Massachu- 

 setts. The age of each district has been determined by 

 fossils which occur, however, only in restricted zones 

 within the formation. The other members are often 

 classed as Cambrian only on conjecture: hence arises 

 considerable difficulty in interpreting the conditions of 



