DELANOUE METAMORPHIC ROCKS. 7 



varians, Gryphcea columbay &c. ought to be regarded as the upper 

 cretaceous terrain, to distinguish it from the gault, which I shall 

 designate middle chalk ; and from the neocomian, which forms the 

 lowest portion of the cretaceous series. 



9. That the Gault, although little developed, constitutes a terrain 

 of itself, and represents the middle chalk of the Maritime Alps. 



10. That the Neocomian terrain finds its representative only in 

 the greenish sandstone characterized by lower neocomian fossils. 



1 1 . That the compact yellow limestone not so characterized, and 

 subjacent to the lower neocomian, is Jurassic ; a conclusion ren- 

 dered necessary by the Jurassic fossils found in it. 



1 2. That the Cretaceous terrains of the Maritime Alps * are limited 

 above by the marly limestone with Inoceramus^ HamiteSy &c., and 

 below by the greenish neocomian sandstone, both inclusive. 



[T. R. J.] 



On the Metamorphism o/* Rocks. By M. J. Delanoue. 



[L'Institut, 1854, p. 285. Leonhard u. Bronn's N. Jahrb. f. Min. u. s. w. 1854, 



p. 731.] 



The author disapproves of the immoderate application of the hypo- 

 thesis according to which silica, natron, and even felspar have been 

 driven out from the interior of the globe to silicify and felspathize 

 not only the strata lying in their immediate vicinity, but even single 

 beds of rock intercalated between others, — or according to which 

 magnesia has penetrated this or that rock, or converted a part of a 

 limestone into dolomite. He does not deny the outbreak of molten 

 rocks from the interior of the earth, and the eifect of their heat on 

 the sedimentary rocks at the point of contact, whereby the latter may 

 have been calcined, and reaction may have taken place among their 

 constituent parts, or many of them may have been volatilized. Thus 

 *'the volcanic rocks are formed by the surfusion of the felspathic 

 rocks ; anthracite and graphite by the heating or calcining of fossil 

 plants, &c. But there is no proof that the porphyries must give up 

 alkalies, or the serpentines carbonated magnesia to rock-masses 

 broken through by them. Thus in the Ligurian Alps the serpen- 

 tines have upraised limestone strata, almost without altering, or at 

 least only fracturing them. Nowhere do we see proofs of the inte- 

 gral chemical change of the whole of a rock or series of rocks." 



* The region which bears tlie general name of " Maritime Alps " extends 

 west and east from near Colmar in France to Capo di Noli, a distance of about 

 90 miles (English) ; and to the northward it has a width, on the parallel of Cuneo, 

 of about 50 miles. 



The principal maps of this district are two. — 1. The great Trigonometric Survey, 

 "CartaTopografica," on a scale of g^^th of nature: the result of operations described 

 in two elaborate volumes 4to. This map occupies ninety (engraved) sheets, and 

 must be an excellent basis for geological survey. 2. A reduction of the great 

 map to a scale of ^q^, in six sheets. (" Carta degli Stati di sua Maesta Sarda, 

 in terra ferma ; opera del Real Corpo di Stato Maggiore; incisa, etc. 1841.") The 

 scale of this reduced map is very nearly 4 miles to an inch (English). — Transl. 



