Professor Keilhau on Contact Products. 147 



notwithstanding this, all such as do not suit the deductions are 

 excluded with the greatest ease as " accidental anomalies.'* 



With respect to the phenomena presented at Melazzo, some 

 expressions of a distinguished geologist, viz. Constant Prevost, 

 can be adduced. Notwithstanding that it is evident, according 

 to F. Hoffman, whose testimony the volcanists will not reject, 

 that the deposition of limestone has taken place on an old, 

 fissured surface of rock ;* yet Prevost finds it difficult to 

 decide " si c'est le calcaire qui a penetre les roches felspa- 

 thiques, ou bten si ce sent celles-ci qui ont passe a travers une vase 

 calcaire.^' The last alternative is adapted for those who wish 

 to see, even here, an effect of volcanic agency ; it is also said 

 that the gneiss has evidently been violently moved since the 

 deposition of the limestone. Moreover, an astonishment is 

 expressed regarding this simple phenomenon, which is in- 

 explicable, if the observer does not, at the same time, mean 

 to say — I have found a gneiss, a granite, and a pegmatite, 

 which were pressed up during the quaternary epoch, and 

 which, as is shewn by the alteration of the limestone, were 

 still hot at so late a period ! The author writes to Cordier 

 in Paris, — " La presqu'ile de Melazzo m'a offert des faits tel- 

 lement curieux que je n'ose en parler sans avoir des pieces 

 de conviction k faire voir en meme temps." When a geolo- 

 gist like Prevost can deceive himself so far ; and when it can 

 be supposed that a geologist like Cordier can be convinced 

 that there exist granite, gneiss, &c. which have been solidified 

 either at or since the quaternary period, merely by having 

 placed before him specimens of these rocks, with attached 

 indurated quaternary limestone, we have signs which bear 

 evidence that the science is not in the best possible condition. 

 In the present case, in order to make all surprise vanish, and 

 to render every absurd supposition superfluous,! it is merely 

 necessary to group the fact in a natural way, and to place it 

 along with other analogous cases in such a manner, that true 



* " There can be no doubt as to the infiltration of the limestone, which has 

 penetrated the gneiss to a depth of ten feet beneath the surface." (Karsten's 

 Archiv.j xiii. p. 345.) 



t I think it necessary for me to say expressly, that I do not mean to assert 

 that it is impossible that granite can have been produced at the quaternary epoch. 



