136 Proceedings of the British Association. 



escarpments, as seen in ravines and sea- cliffs, and wherever nature 

 has exhibited them ; and I affirm, that these sections prove the truth 

 of our arrangements. Even where there are exceptions, they do not 

 vitiate our arrangements ; for we can give a rational explanation of 

 them, and, by showing them to be exceptions, they confirm our pre- 

 vious conclusions. The Dean of York objects to Dr. Buckland's 

 account of the formation of the various strata which succeed these 

 first-formed mineral masses, and proposes, instead, a theory of his 

 own, by which, he says, " every phenomenon can be explained ;" and 

 as it is one thing to find fault with a theory, and another to propose 

 a better explanation, perhaps it will be well to compare the Dean's 

 hypothesis with the actual facts, in the order he has himself adopted. 

 First, we find a set of strata reposing on those before mentioned, 

 and evidently formed from them by the mechanical action of tidal 

 currents and surf beating upon shores ; stratified rocks containing 

 no fossils, either because their structure has been altered by crys- 

 talline action, or because they were formed before the existence of 

 organic life — a supposition which appears to be the more probable, 

 since in passing through the successive strata above them, in des- 

 cending order, we find the number of species, and of types also, 

 gradually diminish, still we arrive at a point where they appear to 

 cease altogether. Upon these again we find sedimentary rocks con- 

 taining fossils, and beds of limestone, which are nothing more than 

 ancient coral reefs, for we can trace the corals as they grew, and see 

 that they are all absolutely distinct from any now existing ; and 

 with these are beds of bivalve shells, not scattered at random and 

 broken by violence, but lying in pairs, where they lived and died, 

 and were quietly entombed. And out of all the multitude of species 

 which then existed, surely some would have survived the changes 

 which succeeded, and still be found in our own seas, if, as the Dean 

 York supposes, those changes were limited to a few days in their 

 operations. Next to these Silurian rocks, as they are called, is the 

 old red sandstone, — a system many thousands of feet thick in 

 Scotland, most of it being coarse conglomerate, formed of pebbles 

 worn round on a sea coast, and requiring an enormous lapse of ages 

 for their formation. With these are occasionally found beds con- 

 taining fish of forms strange and unknown at the present day, and 



