MINERALOGY. 397 



tions, which owe their origin entirely to volcanic agency, 

 and are found in heaped-up fragments everywhere on the 

 surface of the earth. Basaltes are evidently traceable 

 to craters of subterranean volcanoes, 'having arisen from 

 them in the epoch of their activity, and bursting through 

 all opposing matter, formed thick deposits, which, on 

 cooling, exhibited large heaps of lava-like substances, 

 forming isolated masses, as bosses, hillocks, or regular 

 columnar shapes, divided into prismatic pillars.* The 

 Palisades on the North River are examples of basaltic 

 columns. 



From these statements, it is therefore plainly deduced 

 that the primitive formations of stratified and unstratified 

 rocks were originated either by upheaval or depression 

 of the earth's crust, by the action of fire, or formed by 

 sedimentary deposits left by the moving mass of waters, 

 which, as above stated, in their headlong course, exca- 

 vated valleys, formed hills of alluvial detritus, and, pro- 

 ducing great changes, finally left its effects on the sur- 

 face of the earth, as is everywhere apparent at the pres- 

 ent day. These are called primary (stratified) rocks. 

 Those which, in the earliest antediluvian period were 

 formed by upheaval or owe their origin to the exploding 

 force of volcanic action, escaped from the bosom of the 



* De la Beche divides all rocks into two great classes, Stratified 

 and Unstratified. The latter he treats as a single family ; the former 

 he subdivides into ten groups. (See De la Beche's " Manual of Geo- 

 logy," p. 38. Lyell's first class embraces only alluvium, and is called 

 Recent ; the second contains, and is named the Tertiary, diluvium 

 being included in the upper part ; the third class he denominates 

 Secondary, which extends to the bottom of the old red sandstone ; 

 next succeeds his Primary Fossiliferous Class, which includes all the 

 remaining fossiliferous rocks. His Metamorphic Rocks embrace all 

 the stratified non-fossiliferous groups. The unstratified rocks are 



