462 C. SCHUCHERT PALEOGEOGRAPHY OF NORTH AMERICA 



by the Green Mountain axis and on the east by the New Hampshire range. 

 It contains, according to Dana, fr Lower Silurian, Upper Silurian, and 

 Devonian beds in the state of metamorphic schists . . . and crys- 

 talline limestones, but nevertheless affording fossils of each of the eras for 

 their identification; and containing also the Connecticut Valley sand- 

 stone." 



The "Acadian trough" of Dana 71 begins 



"in northern Newfoundland west of the northern part of Long range, and ex- 

 tending to St. George bay and Cape Ray, in southwestern [Newfoundland] ; 

 passing thence over the region of the Magdalen Islands, in the bay of St. Law- 

 rence to Nova Scotia and New Brunswick on either side of the bay of Fundy ; 

 and thence to the region of Boston and Massachusetts Bay, and to that of 

 Narragansett Bay in Rhode Island ; and including rocks from the Cambrian to 

 the Jura-Trias as identified by fossils." 



The northern end of this trough to the Bay of Fundy region is well 

 established, but the southwestern portion in Massachusetts and Ehode 

 Island is based on Cambric and Pennsylvanic deposits. The former may 

 be correctly placed in this depression, but the latter are fresh-water de- 

 posits that have the strike of the New Hampshire range. To the writer, 

 therefore, they appear to form a local structural basin having no relations 

 with the Acadian trough. The latter also includes the "Fundy basin" of 

 Dana (1890, 37), an area which was receiving marine deposits as late as 

 the Oriskanian. 



The Saint Lawrence sea continued across northern and medial New- 

 foundland, along the basin of Exploits river, and thus was in direct connec- 

 tion with the North Atlantic. This is the "Exploits trough" of Dana. 72 

 This trough extended "along Exploits river across Newfoundland, south- 

 westward, to La Poile bay and White Bear river, the length 200 miles." 

 The main or southern mass of Newfoundland appears to have been land 

 since Proterozoic times, and was smallest during the Lower Cambric, 

 when it was overlapped not only in the north, but also in the south. Sub- 

 sequent to the Cambric the southern portion of Newfoundland has been 

 land continuously, while most of the northern or peninsular region was 

 attached to Ungava after Ordovicic time. Exploits channel continued at 

 intervals beneath the sea until about the middle of the Mississippic, when 

 it was added permanently to the land. 



Sonoran sea. — This was a fairly persistent Paleozoic continental sea ex- 

 tending across northern Sonora, southern Arizona and New Mexico, and 



71 Dana : American Journal of Science, vol. 39, 1890, p. 380. 



73 Dana : American Journal of Science, vol. 39, 1890, p. 381. Manual of Geology, 

 1895, p. 461. 



