39-i M. Keilhau"'s Theory of Granite and other Rocks. 



ample of the so-called " StUF'' (literally stalk) a phenomenon so 

 anxiously sought for under basaltic summits, &c. This strong 

 presumptive proof, however, lias some material defects, which 

 we, in our triumph, must not overlook ; at the sides of the 

 vein are beds of sandstone, which are in all respects unchanged, 

 andfriction conglomerates f " Frictions Conglovierater' ) which 

 ought certainly to be expected here, ai'e not to be found. As 

 to what relates to the conglomerates, which, as has been men- 

 tioned, occur among the rocky masses composing the por- 

 phyry districts, they never contain any other fragments but 

 those of porphyry, and they partly lie in such a manner invol- 

 ved in the midst of true prophyries, that they cannot possibly 

 be regarded as friction-conglomerates. 



Eurite-Porphyry, Greenstones, Sfc. — The remaining abnor- 

 mal formations of the territory of Christiania, occur in far less 

 considerable masses than those of which we have hitherto treat- 

 ed. They have sometimes the form of beds ; and sometimes 

 that of veins, according to the usual rule, that allows us to i-e- 

 gard each of them, taken as a whole, as a vein. The red porphyry, 

 or, as it is termed in petrographical descriptions, eurite-por- 

 phyry, is, for the most part, intermingled with the stratified 

 rocks in such a manner, that the flat masses which it forms are 

 parallel with the strata ; but there are also to be found some 

 individual examples in which it presents the most distinct veins. 

 It is remarkable, that, in by tar the greatest number of casci, 

 it is confined to the places where the clayslate formation occurs 

 in the foraiof alum-slate, and it is also a sti'iking phenomenon, 

 that the alum-slate never seems altered when in contact with 

 the porphyry, even where it occurs having a thickness of not 

 more than a line, as may be distinctly seen in several places in 

 the immediate neighbourhood of Christiania. Sometimes there 

 is no slate present between the beds of porphyry, which never- 

 theless occur as distinct beds, and often succeed one another in 

 pretty considerable number. In such cases it is perfectly evi- 

 dent, that they can by no means be the actual results of lateral 

 injection ^ according to the Plutonian view of the subject, wo can 

 only suppose a repetition of effusions corresponding to the num- 

 ber of the beds, by which the matter of the porphyry each 

 time flowed out over the uppermost of the already existing, 

 and at that time perfectly horizontal beds.. Although many 



