term " Dyas 3> to the " Permian }> Group of Rocks. 67 



America no other term in reference to this group has been used for 

 the last fifteen years. 



The chief reason assigned by Geinitz for the substitution of the 

 word " Dyas " is, that in parts of Germany the group is divided into 

 two essential parts only — the Eoth-liegende below, and the Zechstein 

 above, the latter being separated abruptly from all overlying de- 

 posits. 



Now, not doubting that this arrangement suits certain localities, 

 I affirm that it is entirely inapplicable to many other tracts. For, 

 in other regions besides Russia, the series of sands, pebbles, marls, 

 gypseous, cupriferous, and calcareous deposits form but one great 

 series. In short, the Permian deposits are for ever varying. Thus 

 in one district they constitute a Monas only, in others a Dyas, in a 

 third a Trias, and in a fourth a Tetras *, 



In this way many of the natural sections of the North of Germany 

 differ essentially from those of Saxony ; whilst those of Silesia differ 

 still more from each other in their mineral subdivisions, as ex- 

 plained in ' Siluria,' 2nd edition, particularly at p. 342. Near the 

 northern extremity of the Thiiringerwald, for example, and espe- 

 cially in the environs of Eisenach, an enormous thickness of the 

 Roth-liegende, in itself exhibiting at least two great and distinct 

 parts, is surmounted by the Zechstein, thus being even so far tripar- 

 tite, whilst the Zechstein is seen to pass upwards to the east of the 

 town, by nodular limestones, into greenish and red sandy marl and 

 shale, the " Lower Bunter Schiefer " of the German geologists. The 

 same ascending order is seen around the copper-niining tract near 

 Reichelsdorf, as well as in numerous sections on the banks of the 

 Fulda, between Eotheburg and Altmorschen, where the Zechstein 

 crops out as a calcareous band in the middle of escarpments of red, 

 white, and green sandstone f. 



But in showing that in many parts of Germany, as well as in 

 England, the Zechstein has a natural, conformable, and unbroken 

 cover of red rock, I never proposed to abstract from the Trias any 

 portion of the Banter Sandstein or true base of the group, as re- 

 lated to the Musehelkalk by natural connexion or by fossils. I 

 simply classed as Permian a peculiar thin red band (Bunter Schiefer), 

 into which I have in many localities traced an upward passage from 

 the Zechstein, and in which no triassic shell or plant has ever been 

 detected. 



On my own part, I long ago expressed my dislike to the term 

 Trias ; for, in common with many practical geologists who had sur- 

 veyed various countries whore that group abounds, I knew that in 



* Sec ' Siluria,' 2nd edit., 1859, and ' Kussia in Europe and the Ural Moun- 

 tains,' 1845. 



f On two occasions (1853-4) Professor Morris accompanied me, and traced 

 with me these relations of the strata ; subsequently, when Mr. Rupert Jones 

 (1857) was my companion, we saw other sections clearly exhibiting this upward 

 transition which I have described. Since then, Professor Ramsay, when at Eise- 

 nach, convinced himself of the accuracy of the fact that the Zechstein passes 

 up conformably into an overlying red cover. My note-books contain many 

 additional evidences, which I have not thought it necessary to repeat. 



F2 



