Geological Society. 



48? 



clature; whilst nearly all parties are in unison as to the fundamental 

 fact of referring the slates of South Devon and Cornwall to the epoch 

 of the old red sandstone formation. The term grauwacke, however, 

 I rejoice to think, will not be condemned to the extirpation which 

 has been threatened from the nomenclature of geology; it may still 

 retain its place as a generic appellative, comprehending the entire 

 transition series of the school of Freyberg, and divisible into three 

 great subordinate formations: — the Devonian system of Sedgwick 

 and Murchison being equivalent to the upper grauwacke, the Si- 

 lurian to the middle grauwacke, and the Cambrian system to the 

 lower. 



In this threefold distribution of the vast series of strata which 

 have hitherto been indiscriminately designated by the common term 

 grauwacke, we are, as it were, extending the progressive operations 

 of a general inclosure act over the great common field of geology ; 

 we propose a division, founded on measurements, surveys, and the 

 study of organic remains, analogous to that of the secondary strata, 

 from the chalk downwards to the coal formation, established by 

 William Smith, and to the separations of the once undivided ter- 

 ritory of the great teriiary system, effected by Cuvier and Brongniart, 

 Desnoyers, Lyell, and Deshayes. 



To the uninitiated in geology, rectifications in the distribution 

 of strata upon so large a scale may seem calculated to shake confi- 

 dence in all the conclusions of our science ; but a contrary inference 

 will be drawn by those who know that these corrections have never 

 been applied to conclusions established on the sure foundation of 

 organic remains, but to those rocks only of which the arrangement 

 had been founded on the uncertain character of mineral compo- 

 sition. 



FOSSIL VEGETABLES. 



Mr. Barber Beaumont, in a communication respecting these same 

 trees, considers that no drifted plants occur in coal fields, and that 

 all the vegetables which are now converted into coal, grew upon 

 swampy islands covered with luxuriant vegetation, which accu- 

 mulated in the manner of peat bogs; that these islands, having 

 sunk beneath the sea, were there covered with sand, clay and shells, 

 till they again became dry land, and that this operation was repeated 

 in the formation of each bed of coal. In denying altogether the pre- 

 sence of drifted plants, the opinion of the author seems erroneous ; 

 universal negative propositions are in all cases dangerous, and more 

 especially so in geology : that some of the trees which are found erect 

 in the coal formation have not been drifted, is, I think, esta- 

 blished on sufficient evidence ; but there is equal evidence to show 

 that other trees, and leaves innumerable which pervade the strata 

 that alternate with the coal, have been removed by water to con- 

 siderable distances from the spots on which they grew. Proofs are 

 daily increasing in favour of both opinions : viz. that some of the 

 vegetables which formed our beds of coal grew on the identical 

 banks of sand and silt and mud, which being now indurated to 

 stone and shale, form the strata that accompany the coal; whilst 



