4 



INTRODUCTION. 



Though, undoubtedly, such reasons deterred many from grappling with this inquiry, 

 it must not be supposed that the ancient strata have not been studied by enlightened 

 observers. In Great Britain we may cite the names of MacCulloch, Greenough, and 

 Sedgwick, as those of men prominently distinguished in throwing light upon them : — 

 the first by long examination of the Scottish mountains and numerous writings upon 

 them ; the second by his map of England and Wales • the last by his exposition of the 

 order of the rocks in the north of England, a portion of which task Professor Phillips 

 has since followed out, by publishing a monograph of the carboniferous strata. But 

 these authors had not the peculiar advantages which have fallen to my lot ; for in the 

 regions which they studied, there is generally an abrupt boundary-line or break between 

 the older and newer systems. For example, in Scotland there is no sequence of fos- 

 siliferous strata beneath and connected with the Old Red Sandstone ; neither is there 

 such a sequence in Cumberland, Westmoreland, nor the adjacent tracts of Yorkshire, 

 nor even in Devonshire, where some of the oldest masses exist. In fact, a perfect and 

 unbroken series of links, connecting these older rocks with the younger deposits, does 

 not occur in any portion of these islands which had been previously examined. 



On the continent, where great attention had been bestowed upon the older and 

 crystalline rocks, from the days of De Saussure and Werner to our own, the same 

 belief was impressed on the minds of geologists, that the great dislocations to which 

 these ancient rocks had been subjected, had entirely dissevered them from those 

 fossiliferous strata with which we were well acquainted. In short, there existed no 

 foreign work in which rocks of this age were classified according to a law, founded 

 upon superposition and characteristic organic remains. 



But to proceed to facts connected with our own country. No one was aware of 

 the existence below the Old Red Sandstone, of a regular series of deposits, con- 

 taining peculiar organic remains. For example, although it was supposed, that the 

 limestone of Dudley was of greater antiquity than the Old Red Sandstone, no one 

 had observed that those deposits were connected by an intermediate formation of very 

 considerable dimensions, full of organic remains. It is this formation, now termed 

 the "Ludlow Rocks," which seems to have most escaped attention, whilst, from its 

 position, as will appear in the sequel, it is the key which accurately reveals to us the 

 relations of the inferior masses to the overlying strata with which we formerly were 

 acquainted. 



Of the few memoirs which had been published in the Geological Transactions, relating 

 to parts of the region illustrated, the earliest are by Mr. A. Aikin. That accurate ob- 

 server had formed a project of describing Shropshire in detail; but having long 

 abandoned his intention, he no sooner heard of the progress I was making in the 

 present work, than he placed at my disposal his original notes and drawings, illu- 

 strative of certain tracts around the Wrekin and the Caradoc. In truth, at the early 

 period when Mr. Aikin undertook the task, it was almost hopeless to attempt to unravel 



