Outlines of Geology. 77 



' The arrangement which I propose to adopt in the present course 

 is too simple and obvious to need any detailed explanation. We 

 shall commence with an examination of the superior or uppermost 

 strata, and more particularly examine into that wonderful history 

 of the devastation and destruction of a former order of things 

 which is exhibited by the various alluvial and diluvial matters 

 that cover the uppermost of the secondary strata. 



These secondary strata we shall then examine in their natural 

 succession — the chalk, with its contents and accompaniments will 

 claim much of our notice ; and here, and in the superincumbent 

 beds, we shall find brick, earth, potters' clay, and various other 

 products applicable to the arts ; here, too, we shall discover 

 the seat of those subterraneous rivers, which, flowing from more 

 elevated situations, make their appearance at different depths, and 

 in different strata, constituting the various springs of hard and 

 soft water about the metropolis. 



The next substances that occur, are the varieties of freestone 

 used in rough sculpture and building, such as those of Bath and 

 Portland, with their various argillaceous concomitants ; and to 

 these succeed the red sandstone and marl strata in which are 

 our deposits of rock salt, and with which are associated the still 

 more important formations of coal and iron-stone ; the whole of 

 these strata covering a vast extent of country, lie in enormous 

 cavities or basins bounded by that variety of marble, conmionly 

 called mountain limestone, in which, in Derbyshire, and several 

 of the northern counties, are also various subterranean treasures, 

 and whence, more especially, are derived the enormous supplies 

 of lead which enrich the British market. The tnily metalli- 

 ferous formations, or those rocks and strata in which the veins of 

 the great mining districts of England occur, will now be exposed 

 to our view ; and we ultimately arrive at granite and its associates, 

 which form the great and primaeval mountain chains of the world, 

 -and upon which, as far as our limited inquiries enable us to ascer- 

 tain, all the other rocks are incumbent. 



Having thus examined the strata of our globe in the order of 

 their succession, from the surface downwards, I propose to de- 



