52 



Featherstonhdiigh^s Geological Report. 



this formation with great ability and detail as it exists in the 

 north of England, considering it the equivalent of the zech- 

 stein* of Germany. In Nottingham, Derbyshire, Yorkshire, 

 and Durham, however, it differs essentially in structure and 

 arrangement, consisting of marly slates and compact and shelly 

 limestones, with a great central deposite of yellow magnesian 

 limestone, both compact and laminated. Some of the beds 

 have an extraordinary quantity of magnesia contained in them, 

 whilst others, with irregular concretions of crystalline lime- 

 stone, have no magnesia, but occasionally an oolitic structure. 

 The fossil fishes found in this formation resemble those of the 

 kupferschiefer or copper slate of Germany. The German beds 

 of this formation are provincially called " asche," (the loose 

 marl,) " stinkstein," ( fetid limestone, ) rauchwache, zechstein, 

 and kupferschiefer. The rauchwache, when very porous or 

 rather cellular, has often a thickness of from forty to fifty feet. 

 The kupferschiefer has a mean thickness, in the Mansfeldt 

 country in Thuringia, Franconia, and the Hartz, of about one 

 foot. 



The new red or variegated sandstone is named after the 

 colors red, white, blue, and green, which distinguish this rock. 

 In some parts of Germany it includes conglomerates. Rock 

 salt and gypsum are found in it. Occasionally the mica it con- 

 tains is sufficiently abundant to render it schistose. 



The muschelkalkj which is deficient in Great Britain, is a 

 gray compact limestone, passing into marls. 



The variegated marls of the Vosges pass into the lias, the 

 superincumbent formation. They are generally of a red and 

 greenish color, and contain dark schistose seams and thin beds 

 of quartzose sandstone. Salt and gypsum are found in the in- 

 ferior part. The passage of this rock into the lias is not 

 marked in England by these characteristic marls. If there are 



* Formerly the provincial name of a single bed, now the scientific name of a 

 series of beds. 



