SILLIMAX'S INTRODUCTION. 15 



among the Rocky Mountains, and between them and the Pacific ; 

 for all our travellers attest the existence of immense regions covered 

 with scoriae and other decidedly igneous products, as if there had 

 been actual and vast eruptions, within a period too short for decom- 

 position to have reduced those tumefied and semi-vitrified masses 

 into soil. 



Trap and Basalt. — Regular formations of trap, and of basalt with 

 symmetrical columns, are common among and beyond the Rocky 

 Mountains, and the rocks of this igneous family are frequent in 

 many parts of the old United States. They abound in New England, 

 New Jersey, and the Carolinas, and, as usual elsewhere, they 

 protrude their dykes among the rocks. In New England, and 

 especially in New Hampshire, they often divide the primary rocks, 

 cutting even granite mountains from top to bottom ; branching out, 

 in many places, with numerous veins either dying away to extinction, 

 or, perchance, returning again to the main current after having cut 

 off a portion of the invaded rock. The TThite Mountains of New 

 Hampshire abound in such phenomena. 



Similar intrusions are found in the mountains of Essex, Lake 

 Champlain, New York, and in many other places, and the primary 

 rocks on the coasts of Massachusetts and Maine, as well as in the 

 interior, are wonderfully cut up by invading veins and dykes of trap, 

 basalt, and porphyry, and even of granite itself. It appears, also, 

 that in the state of New York, limestone and other rocks, including 

 the primary, and not excepting granite, are traversed by intrusive 

 trap* 



Tertiary Formations. — Our tertiary formations are exceedingly 

 extensive, and are rich in fossil remains. They bound a large 

 portion of the sea coasts south of New England, quite to the 

 Mexican gulf, and up the Mississippi and Missouri : these oceanic 

 deposits are also found, extending hundreds of miles into the in- 

 terior from the coasts, where, as well as near the sea, they furnish, 

 in their calcareous marls, inexhaustible resources for agriculture. 

 Even on the shores of New England, there are marine tertiary 

 deposits, as at Gay Head, in Martha's Yineyard, and elsewhere in 

 that vicinity ; while there are, in every part of the United States, 

 innumerable inland deposits of fresh water tertiary. 



Boulders. — In boulders and rocks of transport our country 



* See Professor Hall, in the Geological Reports for 1838. 



