166 Professor Keilhau on Unstratified 



composed of gneiss, it is alleged that the original slaty mass, 

 some miles in thickness, has been heated through and through 

 from the internal general reservoir of melted materials. But 

 what as to the many cases where we find the transmuted beds 

 high up in series, which contain unaltered strata under the 

 altered \ The answer is, the altered strata there are no longer 

 in their original situation ; either they have separately been 

 elevated to the place which they now occupy, or the whole 

 series of strata has been reversed ! It is really remarkable 

 that people will so designedly deceive themselves. The geo- 

 gnostical facts on the subject are to such a degree speaking, 

 that although they have hitherto been but very superficially 

 considered, and then only regarded with a prejudiced eye, yet 

 individual geologists have been induced to waver regarding the 

 hypothesis of the action of heat. We now hear something of 

 electrical and other non'thermal actions, which were in operation 

 during indefinitely long periods, and which, along with the 

 high temperature, have contributed their assistance to pro- 

 duce the changes. — (Lyell's Elements, p. 251.) 



But why will geologists not place entire confidence in what 

 the natural phenomena teach with such clearness? By stop- 

 ping half way, it remains equally impracticable, as we have 

 seen, to give an explanation in which chemical experimental 

 observation shall not be anticipated, while, on the other hand, 

 a true apprehension of the facts is prevented, and a check is 

 put to farther advancement. 



UNSTRATIFIED CRYSTALLINE SILICIDE ROCKS. 



We have still to speak of the unstratified crystalline silicide 

 rocks. The prevailing erroneous ideas regarding the forma- 

 tion of the crystalline slates, of contact-products, of marble, 

 dolomite, &c., have, in fact, been caused by the view enter- 

 tained respecting the unstratified silicide rocks. It was here 

 that the irrational principles of investigation first came into 

 operation, and here, that method which has so undeservedly 

 come to be regarded as the true philosophical one, especially 

 found its application ; the other questions were mere acces- 

 saries to that respecting the last mentioned formations. 



It is said that we must assume that granite, syenite, por- 



