708 



GEOLOGY. 



the different tints of the marls, the system has been called Poikilitic by Mr. Conybeare, 

 signifying mottled or varied ; and Saliferous salt-bearing by others, from its immense 

 deposits of rock-salt. But the new red sandstone is the appellation in most common use, 

 denoting the arenaceous composition of the predominant rock, the colour prevailing in 

 the group, and its more recent date than the old red sandstone, which underlies the car- 

 boniferous system. Argillaceous, calcareous, magnesian, and saline strata marls, lime- 

 stone, niagnesian limestone, and rock-salt, are variously associated with the sandstone. 



Where the system is completely exhibited in England, it presents the following series 

 of beds an arrangement adopted from Professor Sedgewick : 



(Variegated marls. Red, with bluish, greenish, and whitish laminated clays or marls, 

 holding gypsum generally, and rock-salt partially, as in Cheshire. Included in these marls 

 are certain white and grey sandstones. 

 Variegated sandstones. Red sandstones, with some white and mottled portions, the lower 

 parts in some districts (Nottinghamshire) pebbly. 

 Laminated limestones of Knottingley, Doncaster, &c. with layers of coloured marls, 30 or 40 



feet. 



Gypseous marls. Red, bluish, and mottled. 

 Magnesian limestone, yellow and white, of various texture and structure, some parts full of 



fragmentary masses. 



Marl slates. Laminated, impure, calcareous rocks, of a soft argillaceous or sandy nature. 

 Red sandstone, with red and purple marls and micaceous beds. The grits are sometimes 

 white or yellow, and pebbly. When conformable, this sandstone occasionally passes into 

 the coal measures on which it rests. 



It is only in a few places in the north of England that the above series is found entire ; 

 in other parts of the kingdom where the formation exists several members are wanting, 

 and sometimes the whole system is almost exclusively represented by the gypseous marls, 

 or the magnesian limestone, or the red mottled sandstone. The following table exhibits 

 the complete German, English, and French series : 



Middle. 

 200 or 300 

 feet thick. 



Lower. 



Germany. 



England. 



France. 



Keuper marls and grits. Keuper is supposed 

 to be a German miner's term ; but the deri- 

 vation is unknown. 



Muschelkalk a limestone so denominated 

 from its containing an abundance of mollus- 

 cous remains. 



Bunter sandstein mottled sandstone, a name 

 which originated with Werner. 



Stinkstein, fetid limestone ; Rauwacke, cel- 

 lular limestone. 



Gypseous marls - I Gypseous marls. 



Zechstein mine-stone, referring to veins of | Magnesian limestone, 

 copper ore being found in it. 



Kupfer schiefer copper-slate - ! Marl slate. 



Variegated marls and white and grey 

 grits. 



Variegated sandstones 

 Upper limestone 



Marnes Irisees. 



Muschelkalk. 



Gres bigarres. 



Rothe-todte-liegende red dead-lier, indi- 

 cating that the metallic ore in the above 

 deposit has died out, and is not found in 

 the underlying red sandstone. 



Lower red sandstone 



Gres de Vosges. 

 Gres rouge 



It will be seen from a comparison of the above table, that the German series differs 

 from the English in the addition of the muschelkalk ; white the French contains it, and 

 differs from that of the other two countries in the absence of various beds. It has, there- 

 fore, been remarked, as an important fact for the student to bear in mind, that it is by a 

 general analogy in the type, and not by any conventional series of strata, that systems 



are to be identified in different countries. In France, the chain of the Vosges a ridge 



which separates the ancient province of Alsace from that of Lorraine, and stretches 

 northwards into the Bavarian circle of the Rhine consists of granite and primary strata. 



