214 Prof. J. D. Dana on some Results of 



and Jurassic marine fossils and the presence of Cretaceous species 

 in great numbers are well accounted for. 



Professor Hunt has recognized the existence, on the Atlantic 

 border of the continent and outside of it, during the Palaeozoic 

 era and earlier, of an emerged region, and has appealed to 

 various bare Archaean areas in New England and to the north- 

 east, and to the Archaean character of the Blue Ridge, &c, as 

 proof. He has designated the region, badly, as an " eastern con- 

 tinent," and finds in it, with reason, a source for much of the 

 sedimentary material that was used in making the Appalachian 

 and other rocks. Professor LeConte also brings into his views 

 such an elevation, and remarks upon its final disappearance. 

 But neither of these authors states that he regards it as part of 

 a system of oscillations set in motion by the lateral pressure re- 

 sulting from the earth's contraction, and a direct counterpart to 

 the geosynclinal of the Appalachian region. Their views are 

 adverse to such an idea, the subsidence with them being not due 

 to contraction. 



The facts thus sustain the statement that lateral pressure pro- 

 duced not only the subsidence of the Appalachian region through 

 the Palaeozoic, but also contemporaneously, and as its essential 

 prerequisite, the rising of a sea-border elevation, or geanticlinal, 

 parallel with it, and that both movements demanded the exist- 

 ence beneath of a great sea of mobile rock. 



The movement and mountain-making over other parts of the 

 Atlantic border (p. 132), and also the grand double series of 

 events on the Pacific or Rocky- Mountain border (p. 133), 

 sustain and illustrate the same views. The undercrust fire-sea 

 on the Pacific border must have had great length from north-west 

 to south-east — and also great breadth, for the border region is 

 at least 1000 miles wide; and great breadth and great length 

 seem plainly its characteristics even till Tertiary times. And 

 did it continue on through the Tertiary and afford the floods of 

 rock that were poured out from the deep fissures of this long 

 era ? And was it still in existence when the great floods were 

 poured forth over the drift-gravel beds ? 



It is further to be noted that, in the course of past time, the 

 whole continent has had its surface from one side to the other 

 criss-crossed with oscillations and lines of disturbance, from the 

 lateral pressure acting against its opposite sides, whence it is 

 clear that the continental subterranean seas were once conti- 

 nuous. An appeal to the other continents for further testimony 

 is hardly necessary. 



The facts from the ocean seem to demand a vastly greater 

 range for the undercrust mobile layer. The coral-island sub- 

 sidence during the Quaternary and part or all of the Tertiary 



