SHARPE DEVONIAN ROCKS. 19 



from the Coal-measures down to the mafossiHferous slates of the Ar- 

 dennes : — 



Systemehomllier j AmpdUe, psammite, schiste, 



{Calcaire a crinoides, dolomie 

 et calcaire a productus, 

 silex, anthracite. 

 I { Psammite gnsatre, macigno, 



Oii£Lrtzo-scliisi;Gux s ' 



^ " j Schiste grisatre, calcsehiste, 



|_ calcaire, oligiste oolitique. 



{Calcareux Calcaire et dolomie. 

 r Schiste gris fossilifere, calc- 

 sehiste, etcalcaireargilleux, 

 Quartzo-schisteux.x oligiste oolitique. 



Poudingue, psammite et 

 l_ schiste rouge, 

 c. x^ 1. • f Gres, psammites et schistes 



Systemeahnen | gris-bleuatres. 



c, ^v , , , . f Gres et phyllades gris-bleu- 



Systeme coblentzien < a, ^ •' ° 



{Poudingues, gres verts et 

 phyllades rouges-verts ou 

 aimantiferes. 

 Terrain ardennais. 



In the above table there are two important alterations of the views 

 published by M. Dumont in 1830 in the well-known Memoir on the 

 Province of Liege, which have an important bearing on our English 

 classification. In the memoir of 1830 the Systeme quai-tso-schisteux 

 inferieur, following next below the limestone since identified vnth that 

 of the Eifel and of South Devonshire, was divided into an upper di- 

 vision of red sandstone with conglomerate, and a lower division of 

 argillaceous schists ; thus bringing the Red Sandstone formation im- 

 mediately below the Eifel limestone. M. Dumont now recognizes a 

 great series of fossiliferous schists lying conformably below the Eifel 

 limestone, and resting, often unconformably, on the red sandstones. 

 M, Dumont explained the omission in 1830 of the Schistose series to 

 have arisen from his observations being then confined to the province 

 of Liege, in which they are but little seen ; as soon as he extended 

 his inquiries westward into Hainault, and eastward towards the Rhine, 

 the importance of the schistose series became manifest, and led to its 

 separate insertion in its proper place. 



The other change is of detail, and consists in dividing the lower 

 member of the Systeme quartzo-schisteux inferieur, which lies below 

 the Red Sandstone series, into three divisions — the Sysf ernes ahrien, 

 coblentzien et gedinnien, which are grouped together as the Terrain 

 RMnan* . 



The first of these alterations brings the South Devon series into 



* It must be observed that M. Dumont now uses the word Terrain in the sense 

 in which System is often used in England, while his term Systeme is applied to a 

 division only of the Terrain: the terms, being purely conventional, are equally 

 applicable in either sense, but it is unfortunate that they should have received 

 such different applications from different authors. 



c 2 



