260 Naumann on Primitive Formations, 



fied, crystalline, silicated rocks, have been originally formed, and 

 deposited, in the state in which they now appear to us. If we 

 are not able to comprehend the modality of their process of for- 

 mation, we can comfort ourselves with the adherents of ultra-meta- 

 morphism, who are quite as much at a loss. After all, it is per- 

 haps immaterial whether we assume a problematical process of 

 alteration, or a problematical process of formation ; but if we 

 were, once for all, to choose between one of the two enigmas, 

 we would probably rather prefer the latter, which at least 

 is in unison with the state of the facts. A second objection 

 against the too wide application of the metamorphic theory, 

 arises out of the fact that many gneissoid rocks shew undoubted 

 evidences of an eruptive origin, and that granulite also, which is 

 so nearly related to gneiss, sometimes occurs under such circum- 

 stances as appear to demand for it an eruptive mode of formation. 

 If this is really the case, it is a proof that certain cryptogenous 

 rocks are decidedly not of metamorphic origin. 



The great resemblance which gneiss and the most of the rocks 

 accompanying it, bear to granite and other eruptive rocks ; the 

 probability that the most of these eruptive rocks have been solid- 

 ified from a state of igneous fluidity ; the almost unavoidable as- 

 sumption that our planet was originally in the same state, and 

 was only later covered with a solidified crust; finally the fact that 

 in the primitive gneiss formation, granite and gneiss are found 

 regularly interstratified with each other, have called forth the 

 second of the hypotheses prevailing at present; namely, that the 

 primitive formations form the first solidified crust of our planet. 



This hypothesis has not indeed found so many supporters* as 

 that of the metamorphic origin of the primitive rocks, neverthe- 

 less the objections against it are probably neither greater nor 

 more numerous than against the latter. It leads necessarily to 



* The following geologists support this theory : Fleurian de Bellevue, 

 (Journal de Physique, an XIII) ; Breislak, (Lehrbuchder Geol., I, 372) ; 

 Cordier, in the third part of his celebrated treatise on the temperature 

 of the interior of the earth, (Ann. des Mines 2, s^rie II, p. 120) ; Marcel 

 de Serres ; Kapp, (Neues Jahrbuch fur Min. 1834, 255, and 1843, 326) ; 

 Von Blode, Neues Jahrbuch fiir Min. 1837, 176; De la Beche, Report on 

 the Geology of Cornwall, &c., 1839, p. 31 ; Petzholdt, Geologic, 1840, 

 p. 24, and 1845, p. 35 ; de Roys, Bull, de la Soc. G^ol. XIII, 1840, p- 

 240 ; Scheerer, Karsten and Von Dechen, Archiv. vol. 16, 1842, p. 159 ; 

 Noggerath, Entstehung der Erde, 1843 ; Gotta, Grundriss der Geog- 

 nosie, 1846, p. 161 ; Riviere, Bull, de la Soc. Geol., 2 s^rie VII, p. 327. 



