Geological Society. 



485 



boniferous and Silurian systems, were familiar. It was soon per- 

 ceived, that while some of the South Devonshire fossils approached 

 to those of the carboniferous strata, and others to those of Siluria, 

 there were still many species which could not be assigned to either 

 system ; the whole, taken together, exhibiting a peculiar and inter- 

 mediate palaeontological character. Mr. Lonsdale therefore sug- 

 gested, that the difficulties which had perplexed this inquiry could 

 be removed by regarding the limestones of South Devon as subor- 

 dinate to slaty rocks, which represent the old red sandstones of Here- 

 ford, Wales, Scotland, and Ireland, — their true place in the series of 

 Devonshire being intermediate between the culmiferous basin of 

 North Devon, and the Silurian strata, — if the latter exist in that 

 county. 



The value of this suggestion was not at first appreciated ; but 

 after the lapse of more than a year, Mr. Lonsdale's views were 

 adopted (March 1839) by Messrs. Sedgwick and Murchison*, who 

 soon afterwards applied this new arrangement not only to the groups 

 of Devonshire originally under review, but with a boldness which 

 does credit to their sagacity, extended it to the whole of the slaty 

 and calciferous strata of Cornwall, till then known only as grau- 

 wacke, clay-slate, or killas ; assigning to those strata, likewise, the 

 date of the old red sandstone, and resting this determination entirely 

 on the character of the fossils. This change — the greatest ever 

 made at one time in the classification of our English formations — 

 was announced in a memoir read before the Geological Society in 

 April 1839; the authors then also proposing for the whole series 

 (including both the old red sandstones of Herefordshire, and the 

 fossiliferous slates and limestones of South Devon and Cornwall,) the 

 new name of "Me Devonian system" and expressing their belief, 

 that many of the groups hitherto called grauwacke, in other parts 

 of the British Islands and on the continent, would ere long be re- 

 ferred to the same geological epoch. 



The proposed alteration, therefore, will terminate the perplexity 

 hitherto arising from the circumstance, that the old red sandstone of 

 Werner has been frequently eonfounded with the new red sandstone 

 formation of English geologists. It also explains the cause of the 

 English old red sandstone having been rarely recognised on the 

 continent: — for if the Devonian slates afford the normal type of 



* It is to be observed here, that Mr. Murchison, having previously shown 

 that the fossils of the Silurian <era are distinct from those of the carboni- 

 ferous period, had also pointed out " the vast accumulations" (in which 

 few fossils had at that time been discovered) " then known to separate the 

 two systems." He mentions especially, that " the Jishes of the old red 

 sandstone — entirely distinct as to form and species — are as unlike those 

 of the Silurian system, as they are to those of the overlying carboniferous 

 system :" adding, "that he has no doubt, although at present unprovided 

 with geological links to connect the whole series, that such proofs will 

 be hereafter discovered, and that we shall then see in them as perfect evi- 

 dence of a transition between the old red sandstone and carboniferous 

 rocks, as we now trace from the Cambrian, through the Silurian, into the 

 old red system." — See Silurian System, p. 585, line 22, et seq. 



