35 



1850. — M. Haussman uses the term Thuringer formation. 

 1853. — M. d'Omalius continues the term Peneen. 

 1854-56. — M. Dumont uses the term Peneen. 



1854-59. — Mr. Murchison applies the term Permian, with its signi- 

 fication, as a Russian type, to the XotyeriV^ewi^etZ/S'cmf/stojie, 

 Magnesian Limestone, and marl slate of England ; and also 

 to the Bothliegende, Zechstein, and Bunterschiefer, con- 

 taining the Catamites arenaceus of the Trias of Germany. 

 (Sihiria : 2d and 3d edition.) 

 1859. — M. Marcou shows the objections to the term Permian, with 

 its Russian signification, as a type, and proposes the terms, 

 Saxonian formation, Thuriiigian formation, Eislehenien 

 formation, or " Dyas." 

 1861. — M. Geinitz publishes the first volume of his monograph 

 of the " Dyas," in association with Messrs. Eisel, Lud- 

 wig, Reuss, and Richter. 

 1862. — M. Murchison shows what he calls " the inapplicability " 



of the terms Peneen, Dyas, Trias, Grauwacke. 

 My Memoir, Dyas and Trias (see Archives de la Bibliotheque Uni- 

 verselle de Geneve, 1859), treats two questions entirely distinct. 



The first and the principal one, since it is a reply to the demand 

 for an explanation which Sir R. I. Murchison did me the honor to 

 address to me, shows the numerous and grave objections which arise 

 from the use of the geographical term " Permian," with its significa- 

 tion, as explained by Mr. Murchison, in his work, Russia in Europe 

 and the Ural Mountains, 1845, whether it be applied to Russia itself, 

 or Germany, England, Asia, or America. 



Mr. Mm-chison has declined answering these objections, for the rea- 

 son that " the author had not been in Russia " (see Silliman's Jour- 

 nal, 1859, and Edinburgh Neio Philosophical Journal, 1862J. One of 

 the associates of Professor Geinitz, M. Ludwig, has been to Russia, 

 and the results of his researches will be published in the 2d volume 

 of the monograph of the " Dyas." Other observers will follow, and, 

 before many years have passed, we shall better understand the Rus- 

 sian Dyas and Trias. 



The second question is the union of the Dyas and Trias, as a great 

 geologic period, under the name of " The New Red Sandstone ; " a 

 period which I consider, in time and space, as of the same importance 

 with the Grauwacke or Paleozoic, Carboniferous, Secondary (Ju- 

 rassic and Cretaceous), Tertiary, and recent periods. 



I have never united the New Red Sandstone with the Secondary, 

 or with the Carboniferous. 



In order to work out the classification of the stratified rocks into 

 those grand periods, I have made use of all the geological characters 



