J 92 1. No. 8. ox THE ECLOGITES OF NORWAY. 8 1 



Now, this very rare combinations of igneous rocks has also been met with 

 in the Bergen region, and are there known to be Caledonian. It might be 

 regarded as a strange coincidence if the very analogous fomiation a little 

 farther North were of another age and thus geologicalh- independent of the 

 Bergen igneous complex. No great bearing, however, can be assigned to 

 such a petrologicai analogy when geological ß.ge is being considered. 



The monometamorphic character of the gneiss-formation and its whole 

 series of structural varieties indicating that it has been, during its conso- 

 lidation and shortly after, subjected to an extremely intense stress whose 

 direction, as a whole, is conformable to the strike of the Caledonian zone, 

 would also seem to favour the supposition of a Caledonian age. 



As to the general conclusions which may be drawn from the facts here 

 discussed it is of no consequence, whether the formation has originated in pre- 

 Cambrian or in later times. In any case, however, we must assume that 

 the eclogite-bearing gneiss formation, as a half-consolidated mass, had been 

 brought up from great depths in connection with a great diastrophism and 

 then had been brought near the earth's surface bv a quick denudation, or 

 else no eclogites would have been spared from amphibolitization. 



GARNET IN THE LABRADORITE-ROCK OF 



THE SOGN AREA. 



Inclusions of Olivine-rock in Labradorite-rock 

 near Aurlandsfjord in Indre Sogn. 



In 191 7 Professor Goldschmidt collected, from the East side of Aurlands- 

 fjord in Indre Sogn, South of Sognefjord, large blocks of labradorite-rock 

 containing dark inclusions. The outer zones of these inclusions being 

 garnet-bearing it was to be expected that their investigation would throw 

 some light on the eclogite problem, and Professor Goldschmidt with great 

 courtesy lent me the specimens for stud}-. 



The appearance of one of these large specimens is seen in fig. ii, 

 while the distribution of the minerals is schematically shown in fig. 12. 



The unaltered labradorite-rock in Sogn, according to \'. M. Gold- 

 schmidt ^ generally consists mainly of a plagioclase about Ab4o ^^^ still 

 more anorthitic. At the immediate contact with the inclusions, however, 

 the plagioclase contains 60 pt albite and, in the border-zones, still more, 

 showing a zonal structure. Maximum extinction angles in sections J_ PM 

 are 20". Thus the inclusions are surrounded bv a more albitic zone which, 



' V. M. Goldschmidt, Geologisch-petrographische Studien im Hochgebirge des südlichen Nor- 

 wegens, IV, Übersicht der Eruptivgesteine im Kaledonischen Gebirge zwischen Stavanger 

 und Trondhjem. Vid.-Selsk. Skrifter. I. Mat.-Xatur\-. Kl. 1916, N:o 2, p. 31. 



Vid.-Selsk. Skr. I. M.-N. Kl. 1921. No. 8. 6 



