76 PICTURESQUE SKETCHES 



Yorkshire, in Devonshire, and also in some parts of 

 Ireland, abound with the remains of land vegetables ; 

 and, although there is no doubt that many of these 

 may have been drifted by marine currents, there is, at 

 all events, great probability of the distance from land 

 not having been great. 



It is worth noticing also, with regard to this point, 

 that the carboniferous limestones, or corresponding 

 beds of the same age, skirt the old rocks of Cumber- 

 land, and are deposited in hollows in the devonian 

 rocks of Devonshire and Cornwall; and it is likely 

 that these very rocks themselves, as we know them 

 to have been hardened and prepared for such expo- 

 sure, formed the actual dry land of the period, and 

 that upon them grew the trees and shrubs whose 

 remains are met with in the limestones near them. 

 However this may be, the existence of adjacent land 

 at this time is sufficiently proved; and we may pro- 

 ceed to consider the circumstances of the deposit of 

 the coarse grit and finer sandstones, the upper mem- 

 bers of which were the receptacles of the great masses 

 of vegetable remains now changed into the mineral 

 we call coal. 



It is not improbable, or contrary to what we have 

 reason to think the usual order of nature at present 

 in those parts of the world where coral formations 

 are in progress, that the building up of extensive 

 reefs, of great thickness and extent, should be suc- 

 ceeded by a change in the level of the neighbouring 

 sea bottom. In the case of the carboniferous rocks, 

 this change probably involved the depression of a 

 large tract of land, of whose general form and even 

 direction we are quite ignorant; nor can we even 



