I92I. No. 8. ON THE ECLOGITES OF NORWAY. I9 



limestone in the Archaean of F"inland they present a striking difference in 

 being embedded immediately in formations of a highly crystalline gneiss. 

 No bedded and laminated leptites or other apparent "supercrustal", volca- 

 nogenous or sedimentogenous, rocks can be traced here. If the limestones 

 have originalh' been sedimentary beds, they have, during the diastrophism, 

 been pressed down in the eruptive gneiss magma, and their countrv-rocks 

 have lost all their original characters. 



On Gursko no eclogites occur in immediate contact with the limestone, 

 j. H. L. \'ogt ' records an occurrence of "eclogite near marble" from Brand- 

 saeter near Kornstadtjord. I had a specimen from this locality collected 

 by Prof \'ogt. Its garnet showed n^^ = 1.7525 and was found to contain 

 17.77^ FeO and 8.06^ CaO, conforming to the composition FejiMg^gCago. 

 The specific gravity of the rock is 3.440. Thus it is a true eclogite, and 

 has not assimilated any materials from the limestone. Probably there exists 

 no eenetical connection whatever between the eclogites and limestones. 



The Olivine-rock or Dunite. 



Numerous lenticular bodies of olivine-rock form the largest and most 

 conspicuous inclusions in the gneiss of Nordljord and Mere. Their mode 

 of occurrence and stratigraphical relations to the gneiss have been carefully 

 studied by H. H. Reusch- and J. H. L. \'ogt^. From these surveys the 

 lenses and the foliation of the rock always appear to be conformable to 

 the strike and the band-structure of the adjacent gneiss. The occurrences 

 in Almklovdalen have been folded together with the surrounding gneiss. 

 Largest of all are the occurrences in the region of Tafjord-Sunelvs- 

 fjord in Sendmere and Hornindal in Nordfjord. The rock bodies 

 in the former region form several lenses, some 2 kilometers in maximum 

 breadth, arranged one after another in a narrow zone that may be followed 

 over 20 kilometers along the strike. In Hornindal a single lens attains a 

 length of 12 kilometers. 



Reusch, Brøgger, and \'ogt have all arrived at the conclusion, that 

 the olivine-rocks of Nordfjord and More belong as integrating members in 

 the Archaean metamorphic formation, to which also belongs the gneiss. 

 The olivine-rocks are not by any means intrusive in the gneiss, but they 

 are contemporaneous and both have the same origin, whatever it ma}' have 

 been. This opinion was especially emphasized with great eloquence bj' 

 W. C. Brogger^ who concluded with the following words: "Man könnte wohl 



' j. H. L. Vogt, Norsk marmor. Norges geologiske undersokelse 22, 1897. 



~ Loc. cit. (Forhandl. Vid.selsk. i Christiania, 1877I and: Nye Oplysninger om Olivinstenen 



i Almeklovdalen og Sundalen paa Sondmore. Ibid. 1883. 

 3 Loc. cit. (Nyt Mag. Naturvid., 1883.» 

 ■♦ \V. C. Brogger, Ueber Olivinfels von Sondmore. Neues Jahrb. f. Min. etc.. 1880, 



II, p. 192. 



