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therto been generally referred, and with the utmost confidence 

 to the transition epoch. Many of them appear to me identical 

 with those in the Hartz Mountains, to which the name of grauwacke 

 was in the first instance applied, and which may therefore be con- 

 sidered as the types of that formation. Mr, Smith, indeed, in his 

 geological map of England, refers the Bideford district to the red 

 and dunstone of Brecon and the south-east part of Scotland ; 

 whether he applies that term to the old red sandstone exclusively, 

 or to the old red sandstone and grauwacke conjointly, I do not 

 know ; at all events, neither he nor any other person has ever ex- 

 pressed a suspicion that the beds under our consideration may be 

 more modern than the limestone of Derbyshire; nor am I aware that 

 such suspicion is entertained even now by any one who has seen 

 them in situ. 



Mr. Ainsworth, an active naturalist, who is gone out with Cap- 

 tain Chesney on an expedition to the Euphrates, has published an 

 Account of certain Caves at Ballibunnian on the coast of Kerry, 

 In the bay which bears that name, the cliffs which rise to the height 

 of a hundred feet, are composed of two beds (varying from thirty to 

 forty feet in thickness) of compact ampelite, divided by seams of 

 the same slate but fissile and anthracitous, and pouring out stream- 

 lets of water containing iron and salts in solution. Near Hunter's 

 Path are seven beds of anthracite ; the laminar and slaty rocks be- 

 longing to the great transition clay-slates repose on compact sono- 

 rous argillaceous limestone, and considerable beds of quartz occur 

 in the midst of the slate formation ; this coast, therefore, seems to 

 be very analogous to that of Bideford : it is desirable to ascertain 

 whether the beds of anthracite are here also accompanied by im- 

 pressions of plants, and whether the}'^ can be identified with those of 

 the independent coal districts. 



The distinctness of the Bideford section, and the great ex- 

 perience which Mr, De la Beche possesses in geological surveying, 

 make it highly improbable, I think, that the plants which he has 

 presented to us can belong to any other formation than that to 

 which he has referred them : that the same fossils, vegetable as well 

 as animal, are confined to one particular epoch, and cannot be found 

 in more than one part of the general series, are presumptions, which 

 if countenanced, as to a certain extent they are, by limited expe- 

 rience, more enlarged experience may not unnaturally be expected 

 to overthrow, unless indeed we choose to suppose, amid all the ob- 

 scurity that surrounds us, that our knowledge has already reached a 

 maximum, and that nothing more can ever be visible than that which 

 we have been accustomed to see ; but the case which Mr. De la 

 Beche has stated is not altogether a new case ; it does not even con- 

 tradict our present experience. Coal measures, with their usual 

 plants, have been before found in undoubted grauwacke at the 

 Bocage in Calvados, and you have heard, from one of my pre- 

 decessors, that they occur in the same relative position at Mag- 

 deburg; that they occur in sandstone beds that alternate with 

 mountain limestone in our own country ; and that on the southern 



