INTRODUCTION'. 15 



t 



Hence it appears that the numerical amount of our popu- 

 lation, their varied occupations, and the fundamental sources 

 of their industry and wealth, depend, in a great degree, upon 

 the geological character of the strata on Avhich they live. 

 Their physical condition also, as indicated by the duration 

 of life and health, depending on the more or less salubrious 

 nature of their employments ; and their moral condition, as 

 far as it is connected with these employments, are directly 

 aflected by the geological causes in which their various oc- 

 cupations originate. 



From this example of our own country, we learn that the 

 same constituent materials of the earth are not uniformly 

 continuous in all directions over large superficial areas. In 

 one district we trace the course of crystaUine and granitic 

 rocks; in another we find mountains of slate; in a third, 

 alternating strata of sandstone, shale, and limestone ; in a 

 fourth, beds of conglomerate rock; in a fifth, strata of marl 

 and clay; in a sixth, gravel, loose sand, and silt. The 

 subordinate mineral contents of these various formations 

 are also different ; in the more ancient, are veins of gold 



affords similar examples of the dull uniformity that we observe in a journey 

 along the line of bearing' of tlic clialk, from near Bridport on the coast of 

 Dorset, to Fiamborough Head on the coast of Yorkshire. 



In the same line of direction, or line of bearing of the strata across Eng- 

 land, a journey might be made from Lyme Regis to Whitby, almost entirely 

 upon tiie lias formation; and from Weymouth to the Humber, without once 

 leaving the Oxford clay. Indeed .ilmost any route, taking a north-east and 

 south-west direction across England, will for the most part pass continuouslv 

 along the same formation; wliilst a line from south-east to north-west, at 

 right angles to the former, will no where continue on the same stratum be- 

 }ond a few miles. Such a line will give the best information of the order of 

 superposition, and various conditions of the very numerous strata, that tra- 

 verse our island in a succession of narrow belts, the main direction of which 

 is nearly north-east and south-west. This line has afforded to Mr. Cony- 

 beare the instructive section, from Newhaven near Brighton, to Whitehaven, 

 published in his Geology of England and Wales; along which nearly seventy 

 elianges in the character of the strata take place. 



