122 The Rev. D. Williams's Proofs that the Devonian 



In that very hasty classification (from a very meagre list of 

 fossils only) of Devon and Cornwall with the English Old Red 

 Sandstone, Mountain limestone and Coal-measures, many im- 

 portant facts were overlooked or disregarded, which I am 

 bound to advert to among other plausible reasons against it. 



The Old Red Sandstone, in its ordinary and familiar types, 

 extends from the Orkneys to Monmouthshire, Bristol and 

 the Mendips, and with its Harlequin and other beds, and 

 fishes, is widely expanded in Russia, &c.; yet we are required 

 to believe that in a distance of only twenty miles which part 

 the Mendips from the Quantocks, it reciprocally assumes an 

 opposite mineral and organic contrast^ that in the Quantocks, 

 its conglomerates, cornstones, Harlequin beds and tilestones, 

 have been miraculously metamorphosed into a red quartz 

 rock with hard shales, into several varieties of excellent lime- 

 stone, and a four-mile thick mass of crystalline glossy chlorite 

 and talc slate ; that its thirty or more species of Fishes, which 

 are entombed in the Old Red in such myriads as are described 

 in the vivid and graphic work of Mr. Miller of Cromartie, 

 and its 25 genera and species of shells figured by Mr. Mur- 

 chison, all not only most unaccountably disappear, but more 

 unaccountably are represented by seven or eight species of 

 Siluyicm corals. It surely violates all analogy and probability 

 to suppose tiiat in so short a geological span as exists between 

 the Quantocks and the Mendips, or between Exmoor and 

 Monmouthshire, there should not be something like mutual 

 interpolations of some of their strongly characterized mineral 

 divisions. Why, the Morte slates alone (No. 5.) of Exmoor, 

 if they are an inch, I verily believe are at least four miles in 

 true diametrical thickness, thicker than the Old Red Sand- 

 stone and Silurian together, with 550 feet to spare towards 

 the Cambrian. They rival Dunkerry Beacon in elevation 

 within 58 feet*, and extend from Lundy Island to near Bridge- 

 water, a range of upwards cf sixty miles ; and surely some 

 portion of this vast sediment of such lightly suspended ma- 

 terials would be drifted less than half the distance, to the 

 Mendips or Monmouthshire, if they had been deposited in 

 the same sea and at the same time with the Old Red Sand- 

 stone. 



I must omit the other subdivisions of Exmoor as open to 

 the same objections I have just stated, or to those previously 

 suggested under organic fossils. Major Harding exhibited 

 some fossils at Plymouth fr6m No. 4, which I did not see, but 

 which I understood were considered to be Silurian. No. 6 



• Geol. Survey, De la Beche, page Met scq. 



