I 8 I'KNTTI KSKOI.A. M.-N. Kl. 



M \' 1(1 11 i lie ,i;ii(is-> Irinii \';i n e I \' c ii. I'roni the sliorc-rocks near 

 Torsvik in the p.iiish of Vanclvcn I collected specimens of extremely 

 mvlonitized gneiss, in part derived from an augengneiss and in part from 

 ijanded even-grained gneiss. As usual, this gneiss shows a marked stretch- 

 ing, the axis of which pitches to the liast. Going westwards the rock grades 

 over into an even-grained gneiss free from mechanical deformation. 



The iiiylonitization means deformation of a solid rock. It is a very 

 coiiiiiioii phenomenon, though always of a ver\' limited extent. As was the 

 case in the above example, the strongest mylonitization always occurs in 

 rocks that have suffered strong protoclastic influences. The stress apparently 

 still continued to act after the consolidation had ended, but now its action 

 was limited to certain shearing-planes, the largest parts of the solid rock- 

 masses resisting the stress. 



The Limestone. 



Occurrences of cr3-stalline limestone are faiiiy numerous within the 

 gneiss area of Nordfjord and More (cf. fig. 2 1. The limestone is general!}' 

 coarsely crystalline and, according to C. Bugge (loc. cit. p. i6), contains the 

 following accessory minerals : Quartz, scapolite, white mica, plagioclase, 

 apatite, sometimes also garnet, pyroxene, hornblende, biotite and green 

 mica, occasionally pyrite, graphite and iron ores. 



The rocks bounding the limestone are, in most cases, said to consist 

 of hornblende-gneiss, often garnet-bearing. 



I have myself only visited the limestone of Breivik and Saude near 

 Larsnes, Gursko. The rock there occurs as a very pure layer in almost 

 vertical position more than loo m in breadth. Smaller lenticular layers 

 are embedded in the adjacent gneiss. The immediate contact of the lime- 

 stone is marked by a "contact-wall" that was found to consist of coarse- 

 grained diopside and microcline. The country-rock, in its megascopic features, 

 conforms to the descriptions of the hornblende-gneiss, given by Reusch and 

 Bugge. It is a banded or veined rock, with alternating white "veins" and 

 duller portions containing elongated prisms of a mineral that was believed 

 to be hornblende. By a microscopic examination of a specimen collected 

 from Larsnes, more than one km west of the limestone, I found, however, 

 that this rock is composed of green pyroxene (diopside with a little aegirite) 

 and plagioclase (oligoclase) besides small amounts of biotite and titanite. 

 I have not extended my work to any closer investigation of this \-ery 

 remarkable rock and cannot say whether such plagioclase-diopside rocks 

 have a wide-spread occurrence in the More gneiss area. Probably they 

 are limited to the vicinity of the occurrences of limestone. 



The petrolog}' of the limestones and its country-rocks in More affords 

 many problems of great interest which still remain to be cleared up by 

 detailed field and laborator}- work. Compared with the occurrences of 



