xxviii 



DESCRIPTION OF THE MAP. 



cation), to be entitled to be called " Systems/' from their dimensions, lithological characters, and 

 zoological contents, 



In comparing, however, the rocks of our own land with those of foreign countries, it is not con- 

 tended that each of these systems has a general or even an European range. The Old Red Sand- 

 stone, for example, so vast an accumulation in the British Isles, is scarcely apparent throughout a 

 large part of the continent, while the deposits which I have termed the "New Red System," though 

 thus arranged in England, may not satisfy some geologists of the French or German schools. The 

 latter may contend that in their country, the " Keuper," " Muschelkalk " and " Bunter Sandstein," 

 form a natural group (the Trias), which is separable from the underlying " Zechstein " and " Rothe- 

 todte-liegende " by valid distinctions. In the region, however, which I describe, such distinctions 

 do not exist. On the contrary, all the strata between the Lias and the coal measures are com- 

 posed of red and green marls and sandstones, with conglomerates, both siliceous and calcareous, 

 the lower members of which pass gradually downwards into the Carboniferous System. This 

 subject is fully explained in the work ; and I merely now allude to it, in order to show that in these 

 tracts the natural order of this part of the series consists in the Carboniferous System being over- 

 laid by one red system and underlaid by another. In regard to the subdivisions of the overlying 

 red system, some foreign geologists are, I believe, of opinion that the fossils of the " Zechstein " and 

 " Rothe-todte-liegende " agree better with those of the carboniferous epoch than with those of the 

 overlying red sandstone, but this point is, I am led to believe, far from being satisfactorily adjusted ; 

 for although there may be a species or two of Mollusk common to the Magnesian Limestone and the 

 Mountain or coal Limestone, the great mass of the fossils of the two formations are distinct. That 

 the fishes are distinct has been clearly proved by M. Agassiz, while no researches have yet brought 

 to light a Saurian in the coal measures, though several species of this class occur in the Magnesian 

 Limestone. This last-mentioned zoological distinction is so strong that it seems to me to outweigh 

 in value any conclusions drawn from the Mollusca. Again, if an identity between one or two species 

 of Mollusca is to be made the groundwork for grouping together the Magnesian and Mountain Lime- 

 stone, we may for the same reason connect the Magnesian Limestone with the overlying group (the 

 Trias of the Germans), because the lily encrinite of the Muschelkalk, and, if I mistake not, a cham- 

 bered shell of that rock have been discovered in the Magnesian Limestone. 



As, however, the Silurian region exhibits passages from every formation into the overlying and 

 underlying strata, so must of necessity the lines of demarcation be more or less arbitrarily drawn ; 

 and all that I seek to prove is, that the classification now put forth is best suited to this part of 

 England, however little it may be adapted to other countries. In short, whatever may be the 

 arrangement on the continent, British geologists have reason to claim for themselves the privilege 

 of defining the upper and lower limits of the great Carboniferous System, seeing that it is more 

 copious in our country than in any other part of Europe. 



But to return to my own map. An effort has been made to separate the New Red Sandstone into 

 three distinct bands. For the first time in English geology, the " Keuper Sandstone " is shown to 

 lie in the upper red or saliferous marl 1 , whilst beneath it is the ordinary New Red Sandstone which 

 overlies the "Lower New Red Sandstone," the two last-mentioned deposits being usually separated 

 by a calcareous conglomerate representing the Magnesian Limestone. 2 



1 A memoir on the Keuper Sandstone of Worcestershire and Warwickshire by Mr. H. E. Strickland and 

 myself is in the press, and will shortly appear in the Transactions of the Geological Society. 



* In the map I have made use of three tints of light reddish colour to distinguish, 1st, the PvedMarl and its 



