272 



BASALTIC ROCKS. 



cific shores md the islands, numerous volcanoes ; 

 and it would be strange, indeed, if there were none 

 within our extensive possessions on the same 

 coast." 



There are numerous evidences of volcanic agency 

 among the Rocky Mountains, such as extinct cra- 

 ters, lava, scoriae, and other igneous products. 

 " The whole country," says Mr. Parker,* " from the 

 Rocky Mountains on the east and Pacific Ocean on 

 the west, and from Queen Charlotte's Island on the 

 north to California on the south, presents one vast 

 scene of igneous or volcanic action. Internal fires 

 appear to have reduced almost all the regular rock 

 formations to a state of fusion, and then, through 

 fissures and chasms of the earth, to have forced the 

 substances which constitute the present volcanic 

 form. Such has been the intensity and extent of 

 this agency, that mountains of amygdaloid and ba- 

 salt have been thrown up ; and the same substance 

 is spread over the neighbouring plains, to what 

 depth is not known ; but, from observations made 

 upon channels of rivers and the precipices of ra- 

 vines, it is evidently very deep. The tops of some 

 mountains are spread out into horizontal plains, 

 some are rounded like domes, and others terminate 

 in conical peaks and abrupt eminences of various 

 magnitudes, which are numerous, presenting them- 

 selves in forms resembling pillars, pyramids, and 

 castles. There are several regularly" formed cra- 

 ters; but these, presenting themselves in depres- 

 sions or in cones, are rendered obscure by the lapse 

 of time. That volcanoes have existed there can be 

 no doubt, but that they have been in active opera- 

 tion recently is more uncertain." Mr. Parker also 

 states that nearly all the rocks among the Rocky 

 Mountains are amygdaloid, basalt, lava, and obsidi- 

 an (volcanic glass), which sufficiently prove the vol- 

 canic character of this region. 



* Exploring Tour, &c, p. 208. 



