10 INTRODUCTION. 



deductions, it was indispensable that all the overlying formations should be examined ' 

 and their boundaries laid down upon the map. 



In searching the younger deposits I learnt, that the New Red System was separable 

 into distinct formations, one of the uppermost being found to contain a band of sand- 

 stone with peculiar fossils. Though not previously noted, this rock most clearly re- 

 presents the sandstone of the " keuper " or " marnes irrisees ;" while the central masses 

 of sandstone, both by geological position and the plants they contain, are shown to 

 occupy the place of the " bunter sandstein" or " gres bigarre" of foreign geologists. 



Finally, I ascertained, that within the area of the Silurian region there were na- 

 tural sections, exposing passages throughout the whole series, and thus connecting all 

 the formations from the oolitic to the slaty Cambrian rocks; a most remarkable fact, 

 and one perhaps almost without parallel in any European district of like extent. 



I need hardly say, that these numerous branches of the subject have caused a much 

 longer examination than was originally contemplated and have considerably retarded 

 the appearance of these volumes. Geologists, indeed, require no apology for the delay, 

 as they well know that the illustrations of such a work could not have been rapidly 

 prepared j but from those friends who have not made our science their pursuit, and 

 yet have countenanced my efforts, a larger measure of indulgence is claimed. With 

 the aid, however, of the map, the numerous coloured sections, and pictorial views, it 

 is hoped that this class of readers will not encounter many serious difficulties. As 

 owners of the soil, I hope they may derive some use, not only from the efforts I have 

 made to indicate where coal may be advantageously sought for, but from those which 

 demonstrate where it never can be found ; while a knowledge of the true nature of the 

 sub-strata cannot fail to be of value to the agriculturist. 



In deciphering the history of these rocks, I have worked from the upper or known 

 formations to the lower or unknown, and the reader will therefore be led through 

 a descending geological series. The younger stratified deposits which flank the 

 Silurian territory on the east and north will be first described, and then the inferior 

 sedimentary masses j while the rocks of volcanic origin, and the effects produced by 

 their intrusion amid the strata, will be pointed out in each district in which the order 

 of the beds has been previously established. 



After being thus carried back to remote periods, during which the order of the strata 

 has often been deranged by great dislocations and volcanic eruptions, the reader's atten- 

 tion will be called to the various sorts of superficial detritus of the region, which being 

 formed out of all the solid formations, could not be intelligibly explained without a pre- 

 vious account of the rocks from which it has been derived. In this branch of our 

 subject, the reasons for pursuing a descending order of inquiry no longer existing, the 

 historical method is adopted. Beginning, therefore, with the consideration of the 

 earliest deposited loose materials, the student will have successively placed before him 

 each newer accumulation of gravel or sand, whether entirely marine, or formed during 



