NEGATIVE CONTINENTAL ELEMENTS 451 



this sea from the Saint Lawrence sea by way of the Champlain trough, 

 and during the early Devonic through the Connecticut trough. During 

 much of Paleozoic time, however, the faunas came directly from the 

 Atlantic through New Jersey strait. This connection with the Missis- 

 sippian sea was either a wide one through the Ohio basin or was much 

 restricted by the more or less neutral land Alleghania. In general, it 

 may be said that the faunas of the Appalachian sea were in harmony with 

 those of the Mississippian sea because of their open communication one 

 with another. At times, however, these seas were completely isolated, in 

 which case the Appalachian sea, particularly its northern end, took on a 

 decided Atlantic faunal aspect, and it should be stated that the Appa- 

 lachian sea always showed more of this character than did the Mississip- 

 pian sea. 



During the late Cambric and the greater part of the first half of the 

 Ordovicic the Appalachian sea deposits were in the main of a calcareous 

 dolomitic nature; yet subsequently, when the trough was clearly defined, 

 its sediments were chiefly muds and sands. This was especially true of the- 

 northern portion of the trough, and attained its climax in Devonic times, 

 when 10,000 feet of Middle and Upper Devonic strata were laid down. 49 

 The present writer believes that the major amount of this material came 

 from Acadia, or more specifically from Taconia, and that the cause of" 

 this great thickness was the narrowness of the Appalachian trough, 

 hemmed in on the west by Alleghania. The first restriction of this trough 

 came with the Cincinnati uplift, which was due to the Taconic revolution 

 that began in early Utica time and culminated with the Eichmond. The 

 rise of the more or less neutral land Alleghania was also contemporaneous 

 with this uplift. Ulrich thinks that the first restriction appeared as early 

 as the Lower Mohawkian. He states that these deposits nearly all over- 

 lapped to extinction on its flanks. 



The Appalachian sea was at times divided into two parts by a land area 

 in southern Virginia, when either the northern or the southern portion, 

 or both, may have been occupied by independent marine waters. To the- 

 northern Appalachian sea, extending from New York (west of Taconia) 

 to Virginia (west of Appalachia), the name New York basin is here ap- 

 plied, as the history of this area is best known in the State of New York. 

 The region about Albany, New York, has been called by Dana 50 the 

 "Northeast bay." The southern Appalachian sea may take the name 

 Cumberland basin; it extended nearly from Tennessee to Alabama, where- 



49 Willis : Bull. Geological Society of America, vol. 18, 1907, p. 399. 



50 Dana : Bull. Geological Society of America, vol. 1, 1890, pp. 42-43. 



