178 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 31, 



Fig. 9. — Section at Pusaasen, Christiansand. 



^|i^|g^gpg|gp^|ipi^^^^^ 





a. Gneiss. 



b. Calciferous and augitic gneiss. 



c. Foliated crystalline limestone. 



A. Granite vein (3 feet thick). 



B. Smaller granite vein. 



The foliation here, in the gneiss, in the augitic calcareous gneiss, 

 and in the limestone, is parallel in each rock, and to the general run 

 of the imbedded vein of granite. 



On the coast near Krageroe we have also numberless instances of 

 the foliation of the gneiss having the same direction as the veins of 

 granite may have on an immense scale. Near Smedsbugten v\^e have, for 

 instance, no less than seven enormous veins, or rather beds, of granite 

 visible on the side of the mountain arising abruptly from the sea, and 

 all of vvrhich run N.N.E., dipping to the W. at an angle of about 40°. 

 Betv^^een each of these are great beds of gneiss, the general foHation 

 of which is parallel to the beds of granite, and the whole appears to 

 be several hundred feet in height. 



In the paper by Mr. Dahl and myself, previously quoted, other 

 instances will be found. 



It is frequently also the case, where veins of trap make their ap- 

 pearance, that the foliation is found parallel or greatly influenced. 



On the side of the road about two miles from Inverarnon, in 

 Perthshire, I observed a vein of grey porphyritic trap, containing 

 specks of iron and copper pyrites, and running N.-S., with a dip of 

 20° W. 



On both sides of the trap, the mica-schist, which was quartzy and 

 contained black mica, had the same angle of foliation as the imbedded 

 trap-vein. 



This I found also to be the case about two miles further north 

 from this, where a large vein of syenitic trap, running nearly hori- 

 zontal, showed itself. Here, however, as small veins ramified from 

 the main body of trap, the coincidence was not always so carried out 

 as in the previous case. 



Similar cases to these were found in Drangedal, at Vedfald, where 

 two veins of mottled serpentine-trap made their appearance. 



That the intrusion or approach of igneous rocks is always the cause 

 of foliated structure cannot be insisted upon ; and I am aware that 

 many cases occur exhibiting appearances quite diiferent from the above- 

 mentioned : still at the same time it is a circumstance worthy of con- 



