58 Professor Buckland's Address. 



transfer the culraiferous or anthraeitic shale and grits (Shillot and Dun- 

 stone) of North Devon to the carboniferous sj-stem ; withdrawing them 

 from the greywaeke in which they had before been included, and thus 

 assigning a much more recent date than heretofore to the strata which 

 occupy nearly one-third part of the map of Devonshire. 



But the relations of the slates and limestones of South Devon still re- 

 mained to be determined ; the mineral characters of the former being dif- 

 ferent from those of the old red sandstone beneath the carboniferous group 

 in many parts of South Wales and in Herefordshire, while the true posi- 

 tion of the limestones (e. g. those of Plymouth, Torbay, and Newton 

 Bushell) was doubtful. At this period (1837), the fossils of this dis- 

 trict were examined bj- Mr Lonsdale and Mr Sowcrby, to whom the 

 organic remains both of the carboniferous and Silurian systems were 

 familiar. It was soon perceived, 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 suggested, that 

 the difficulties which had perplexed this inquiry could be removed by re- 

 garding the limestones of South Devon as subordinate to slat}' rocks, which 

 represent the old red sandstones of Hereford, Wales, Scotland, and Ire- 

 land, — their true place in the series of Devonshire being intermediate be- 

 tween 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 originalby un- 

 der review, but, with a boldness which does credit to their sagacity, ex- 

 tended it to the whole of the slaty and calciferous strata of Cornwall, till 

 then known only as greywaeke, clay-slate, or killas ; assigning to those 

 strata, likewise, the date of the old red sandstone, and resting this deter- 

 mination entirely on the character of the fossils. This change — the great- 

 est ever made at one time in the classification of our English formations 

 — was announced in a memoir read before the Geological Society in April 



* It is to be observed here, that Mr Murckison, having previous!}- shewn that 

 the fossils of the Silurian era are distinct from those of the carboniferous 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 fishes 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 pre- 

 sent 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 evidence 

 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 2$, et seq. 



