I, 



n the south-eastern part of the Christiania Fiord we meet, 

 along its eastern shore, with a long series of small islands, or 

 in many cases rather islets or even only skerries, huilt up from 

 different layers of feldspar-porphyry or rhomben-porphyry asso- 

 ciated with tufacious or even brecciated strata of agglomerate, 

 that may in some places appear very nearly like a true conglo- 

 merate, the only characteristic difference proving to be a more 

 homogeneous constitution than is as a rule met with elsewhere 

 in such deposits. At first sight we might easily imagine our- 

 selves to be confronted with some glacial deposit of ancient date; 

 but even on closer inspection it has not as yet been possible to 

 detect any clear evidence in that way, such as glaciated surface, 

 striated boulders, or any other circumstance that would unques- 

 tionably support such a supposition. Moreover, geologists now 

 generally agree in regarding this deposit as of volcanic origin, 

 or at any rate nearly allied to such an action. 



One of these islands is Rauer, situated in lat. 59° 15' N 

 and nearly in the longitudinal meridian of Christiania. In the 

 early part of the summer of 1909, when conducting an excur- 

 sion to the environs of the southern part of the Christiania Fiord, 

 I visited this island accompanied by five university students. 

 On landing on the island, one is irresistibly struck with the 

 great difference in topographical conditions between this island 

 and the neighbouring mainland. We have indeed passed a break- 

 line or a thrust-line between the gneissic and fundamental rocks 

 of the latter, and the much younger rocks of the former. With 

 regard to the quaternary deposits, hovvever, there is no striking 

 difference; for we meet with the same low terraces both in the 



