38 EXPLANATION OF PLATE 26'\ 



which lies in the middle region of that large, and widely- 

 extended series of Sandstones, and Conglomerates, Lime- 

 stones, and Marls, which English Geologists have usually 

 designated by the common appellation of the New red 

 Sandstone Group, including all the strata that are inter- 

 posed between the Coal formation, and the Lias. 



M. Brongniart, in his Terrain de rEcorce du Globe, 

 1829, has applied to this middle division the very appro- 

 priate name of Terrain Poccilienj from the Greek 7rom>.og), 

 a term equivalent to the names Bunter Sandstein, and 

 Gres bigarre, which it bears in Germany and France ; and 

 indicating the same strata which, in England, we call the 

 new Red Sandstone. (See Plate 1. Section No. 17.) 



Mr. Conybeare, in his Report on Geology to the British 

 Association at Oxford, 1832 (Page 379, and P. 405, Note), 

 has proposed to extend the term Pacilitic to the entire 

 Group of strata between the Coal formation and the Lias ; 

 including the five formations designated in our section 

 (PL 1, No. 15, 16, 17, 18, 19), by the names of New Red 

 Conglomerate, Magnesian Limestone, Variegated Sand- 

 stone, Shell Limestone, and Variegated Marl. Some com- 

 mon appellative for all these formations has been long a 

 desideratum in Geology; but the word Pcccilitic is in 

 sound so like to Pisolite, that it may be better to adhere 

 more literally to the Greek root ttoikIt^o;, and apply the 

 common name of Poikilitic group to the strata in ques- 

 tion.^ 



* The general reception of such a common name for all these 

 strata, and the separation of the Grauwacke series into the Cambrian 

 and Silurian systems, as proposed by Professor Sedgwick and Mr. 

 Murchison,will afford three nearly equal and most convenient groups 

 or systems, into which the strata composing the Transition and Se- 

 condary series may respectively be divided ; the former compre- 

 hending the Cambrian, Silurian, and Carboniferous systems, and the 

 latter comprehending the Poikilitic, Oolitic, and Cretaceous Groups. 



