326 Rev. A. Irving — The Permian- Trias Question. 



name), soHansmann in 1850 had proposed "Thiiringer Formation " 

 as a local name, and Marcou had with equal justice proposed the 

 name " Terrain Saxonien " to include the Saxonia both of Germany 

 and England. He goes on to say that " the well-chosen name Dyas 

 (Awas, duality) removes all further ground for the scruple or dis- 

 cussion which attaches itself to every local name. We apply the 

 name Dyas, however, not quite in the same sense as M. Marcou, who 

 regards it as belonging to the Mesozoic series, but rather, with 

 Murchison, reo-ardina; it as belongino- much more to Palceozoic time." 

 It was in 1859 that the name was first proposed by Marcou, then 

 a Professor at Geneva. 



A few more words may fairly be said here (since English geolo- 

 gists will not read German if they can help it), so as to give this 

 obnoxious little name " Dyas " a fair hearing, now that it has been 

 brought into court, before it is finally banished beyond sea,^ 



Geinitz defines the ' Dyas ' as including all the strata between the 

 Carboniferous and the Trias, which both by intimate geological and 

 palasontological character belong to the older formations, and mark 

 the close of the Palseozoic time on our earth. (For a summary of 

 Credner's masterly sketch of the evidence of this, I may refer to my 

 former paper in this Magazine, in 1882.) The name ' Dyas ' points 

 to the close relationship existing between the two formations included 

 under this head. This close relationship is true in a two-fold sense. 

 We have not merely in the ZecJistein a " marine formation with inter- 

 stratified layers of gypsum, anhydrite, rock-salt, and saliferous clays," 

 and in the Rothliegende an " essentially freshwater and land formation 

 with eruptive rocks included among its strata ; " but the latter is, in 

 part at least, parallel with the Zechstein, as Gutbier first pointed out 

 in 1849. Only those who have gone over the ground and seen this 

 parallelism in the field, and the relation, in section after section, 

 which there is between the granitoid conglomerate of the Ober- 

 Eothliegende and the brecciated and conglomeratic sandstones and 

 marls of the Unter-Eothliegende (the former being seen overlying 

 tlie latter in repeated sections around the Thiiringerwald), will feel 

 the full force of the evidence of close relationship between the two 

 great members of the German Dyas, which is drawn from this 

 parallelism. The most important fact, perhaps, about the Ober- 

 Rothliegende is the derivation of its materials entirely from the rocks 

 near by, as shown both by the materials of which it is composed, 

 and the subangular form of its contained fragments ; and this remark 

 is as true of this sub-formation in the syenitic country about Dresden 

 as it is around the skirts of the Thiiringerwald. In neither of these 

 regions is it overlain by any but the upper stage of the Zechstein. 

 These few remarks (which might be very much extended, if space 

 permitted) prepare us for the following tabulation of the Dyas 

 strata, as given by Geinitz in his ' Introduction.' 



1 It is worthy of remark that Professor Geikie has recognized the value and 

 fitness of the term in his new text-book. 



