224 Carl Fred. Kolderup. [Nr. 8 



parts have preserved their original structure and exhibit few 



pressure phenomena, others are again altered into hornblende- 

 schists. 



The Green Gneiss. 



(Pages 63—69.) 



Dr. Reusch, who was the first to study the above species of 

 rock, has designated it as "green gneiss". This green gneiss is 

 rather varying as to composition. A microscopical exaraination of 

 the main type. a greenish folded rock with streaks of black mica 

 found near the railroad, shows the following mineralogical com- 

 position: large folia of a green mica often altered into chlorite, 

 numerous grains or prismes of epidote and in part zoisite, further- 

 more some individuals of a monoclinic pyroxene, comparatively large 

 grains of plagioclase, titanite in no small quantity, and finally some 

 few yellowish aggregates of rutile. By parallel arrangement of the 

 dark mica-folia, and by alternation of lighter and darker parts, a 

 sort of stratification is produced. Sometimes the mica occurs in 

 streaks which do not coincide with the stratification. In several 

 places at the railroad there are seen numerous veins, lenses, and 

 quite irregularly defined lumps of quartz, or less frequently of 

 coarse-grained granite rich in quartz. In some localities irregularly 

 defined lumps of marble are observed; I should be inclined to recog- 

 nize some of the light-eoloured fragments of the latter as original 

 boulders, and in several cases the green gneiss, too 5 presents a 

 structure reminding us of the structure of the strongly pressed 

 polymict conglomerates occurring near by. This is not the case at 

 the railroad alone. but also for instance in the valley north of the 

 farm named Stolpene. Fig. 21 displays the structure of this rock. 



Near Mørkvaag some dyke-formed parts of fine-grained amphi- 

 bolitic rocks are seen parallel to the direction of the strike of the 

 gneiss. Probably these are altered diabases. 



The northern continuation of the green gneiss is found on the 

 south side of Osterøen. The southern continuation is to be sought 

 in the metamorphosed series of lavers at Os (see fig. 1). The so- 

 called chloritic sparagmite which sometimes shows conglomerate- 

 structure too, corresponds probably to the green gneiss. 



