528 



Scientific Geology. 



their strata in Massachusetts, have not been accurate enough to de- 

 cide as to their course within a few degrees. I have found the di- 

 rection of the strata to correspond very nearly with the meridian, ex- 

 cept in anomalous cases. 



Beaumont in his Recherches sur quelques-unes des Revolutions de 

 la surface du Globe* notices cursorily the system that has now been 

 described; and he remarks that "without doubt it belongs to an epoch 

 more ancient than that of the northeast and southwest beds that con- 

 stitute the Alleganys properly so called." He however makes no 

 distinction between what I call the oldest and the newest meridional 

 system; not being aware probably of any evidence of two epochs of 

 elevation. 



In New Jersey and Delaware primary ranges have been described, 

 running nearly north and south, which have been regarded as a pro- 

 longation of those along the banks of the Hudson and the Connecti- 

 cut. They ought rather to be regarded as parallel ridges, belonging 

 however to the same system : and from some hasty observations which 

 I made several years ago in New Jersey, I am disposed to believe 

 that the new red sandstone there, occupies the same relative situation 

 with respect to the primary rocks, as in the Connecticut valley. 



Examining the map of America, we perceive that a considerable 

 part of the Rocky Mountains have a north and south direction, and 

 that such is the general direction of the Andes, as well as of several 

 ridges in South America east of the Andes : and we know that some 

 of these ranges at least, are mainly composed of primary rocks. But 

 in every case, except some of the ridges last named, their difference 

 of longitude is so great as to render it extremely uncertain whether 

 they were elevated at the same epoch as the system that has been un- 

 der consideration. 



2. The Trap System. 



The circumstances connected with the greenstone ridges in the 

 Valley of the Connecticut, are such as to lead me, with not a little 

 hesitation, to regard them as erupted at an epoch distinct from all the 

 periods in which the other rocks in the State have been elevated. 

 On page 243, I have suggested the reasons that lead to the conclu- 

 sion that the greenstone began to be protruded through the sandstone 



*Chap. 2, p. 323. 



