1848.] MURCHISON ON THE STRUCTURE OF THE ALPS. 21/ 



have collected some of the forms in a truly cretaceous rock. My friend 

 M. de Verneuil, Avho visited Kressenberg in 1 847, has informed me that 

 all the fossils associated with the nummulites are of supracretaceous 

 forms. He has satisfied himself that the matrix of the two sets of 

 fossils is quite distinct, the one containing the gault or greensand 

 fossils being an earthy chloritic sandstone, the other a highly quart- 

 zose and ferruginous rock. It is in the latter only, which is sur- 

 mounted by the flyscli, that nummulites occur, including N. Icevigata, 

 Lamk., and N. elegans, Sow., of our London clay, associated \Adth 

 Orbitoidea, D'Orb.; Fygorhynchus Cuvieri, so abundant in the cal- 

 caire grossier of Paris ; Conoclypus conoideus, which, with other 

 species of that genus, is so frequent in the Alps ; and also the 

 Echinolampas politus, Ag., common to the Vicentine and south of 

 France. 



In a word, there can be no sort of doubt in the mind of any geo- 

 logist, who has examined the two localities, that the nummulite rocks 

 of Sonthofen are exact equivalents of those of Kressenberg. The 

 flysch at the latter, as at Sonthofen, is thrown in towards the chain, 

 and differs only from that of Sonthofen in the occurrence of a line of 

 fault between it and the beds containing nummulites. 



Deferring for the present the general consideration of the fossils of 

 the nummulitic rocks, I may remind the reader that they do not con- 

 tain any one of the prominently characteristic types of the chalk, 

 such as Ammonites, Belemnites, Hamites, Inocerami, &c. Hence I 

 think that all geologists who classify strata by their animal contents 

 combined with their order of superposition, must admit that the num- 

 mulite and flysch rocks of the Alps, Savoy, Switzerland, Bavaria and 

 Austria belong to the older tertiary or eocene age, and can no longer 

 be classed with the cretaceous rocks. The only question, it seems to 

 me, which can be mooted is, where the precise line between second- 

 ary and tertiary should be drawn ; — for example, whether, as I think, 

 immediately at the base of the lowest band of nummulites, or still 

 lower beneath the flysch-like and greensand beds {e) with one or two 

 species of Grypheea, of which so much has been said. On this point 

 it is sufficient to say, that wherever a true lithological passage and con- 

 formable transition occur, the settlement of such line of demarcation 

 must always be somewhat arbitrary. 



The opinions of the eminent geologists who have classified the 

 nummulitic and flysch deposits in the secondary rocks, being based 

 upon physical features^ I must necessarily defer considering them, 

 until the whole subject of the relations and fractures of this zone be 

 reviewed. 



Supracretaceous or Older Tertiary Rochs of the Southern Alps 



and Vicentine. 



The greater part of a century has elapsed since Arduini* expressed 

 his belief, that the deposits of Ronca and Bolca, &c. were of tertiary 

 age, and that Fortis remarked how certain species of fossils from the 



* See Ardiiini's Letters. 



