Geology of England and Wales, ^rc." 231 



on this rock, we anticipate, that nothing will be called gray 

 wacke, that does not lie between this rock and the transi- 

 tion argillite. We shall rejoice if it can be confined within 

 these limits: for we really believe, that scarcely a seconda- 

 ry, or traasition rook can be named, which has not, at one 

 time, or another, been denominated gray wacke : and, in- 

 deed, the usual definition of that rock will comprehend 

 them about all, without difficulty. In regard to the primi- 

 tive rocks, to be described in the second part of Conybeare 

 and Phillips' work, we do not expect so much will be pre- 

 sented, that is new and interesting, as in the part of the 

 work, whose analysis we have now given. 



It remains, in this place, to notice the geological map of 

 England and Wales, and the Sections, that accompany the 

 work. Their execution is in the elegant style of the geolo- 

 gical Society. The map is compiled from that of Mr. 

 Greenough ; with some corrections, which subsequent dis- 

 coveries have rendered necessary. The tablets appended 

 to the map, to designate the different formations, amount to 

 twenty- seven-, and the following are the names attached to 

 them. 1 Diluvial Beds, 2 Upper Marine, 3 Fresh Water 

 Beds, 4 London Clay, 5 Plastic Clay, 6 Chalk, 7 Chalk 

 Marie and Green Sand, 8 Weald Clay, 9 Iron Sand, 10 

 Purbeck and Portland, or Aylesbury Limestone and Kim- 

 meridge Clay, 11 Coral Rag and Calcareous Grit, 12 Ox- 

 ford, or Clunch Clay, 13 Cornbrash, Forest Marble and 

 Great Oolite, 14 Inferior Oolite and Sandy Beds, 15 Lias, 

 16 New Red Sandstone, 17 Magnesian Limestone, 18 

 Coal, 19 Millstone Grit and Limestone Shale, 20 Carbon- 

 iferous, or Mountain Limestone, 21 Trap of Coal and 

 Mountain Limestone, 22 Old Red Sandstone, 23 Transi- 

 tion Limestone, 24 Serpentine, 25 Sienite and Trap, 

 Transition and Primitive, 26 Slates, Greywacke and Clay 

 Slate, 27 Granite. How immense the labour of ascertain- 

 ing the boundaries of all these formations ! And how great 

 an advance, from a map, recognizing only primitive, transi- 

 tion and secondary ! Three or four patches of no great 

 extent are left uncolored, for reasons unknown to us.* 



* If we mistake not, these patches are intended for Alluvium. They 

 comprise the Fens of Lincolnshire, Ely and Somerset, a tract along the 

 E. coast of Lincolnshire, others on either side of the Humber, and insula- 

 ted tracts along the coastof Lancashire. These districts are nok only left 

 uncoloured, but are shaded like marshes in common maps. (Ed.) 



