1911] Sogneskollens og Bremangerlanrtets granodioriter. 29 



white granodiorite penetrate the stratas (Fig. 6). I also found 

 metamorphosed fragments of the silurian schists in the granodiorite, 

 especially on the eastern side of Smørhavnsø. All these observa- 

 tions prove that the granodiorite in Bremangerland as well as the 

 white granodiorite from Svanø and Sogneskollen are younger than 

 the Silurian. 



On the southern coast of Smørhavnsø and Bremangerland the 

 white granodiorite is superposed by a breccia containing great an- 

 gular fragments of white granodiorite (Fig. 8). The white granite 

 is here so predominating, that the breccia must be a bottom breccia 

 as it is called by the Finnish geologists. When walking away from 

 the border, we find that the fragments of the white granodiorite be- 

 come less frequent and more rounded, so that we get a brecciated 

 conglomerate (Fig. 9). In the sandstones which are overlying the 

 conglomerate, two of my assistants and I have found plant fossils of 

 devonian age, perhaps these fossils belong to the upper Devonian, 

 In Stockholm I saw similar fossils from the upper Devonian 

 of Spitsbergen. We get here a very good estimation of the age 

 of the granodiorite, it cuts the metamorphosed silurian stratas and 

 occurs as fragments in devonian breccias and conglomerates. 



The White Granites Deseribed and their Plaee in the Petro- 



logieal System. 



Mineralogically the rocks from Sogneskollen, Svanøen and Brem- 

 angerland deseribed above are distinguished by a relative small 

 amount of dark minerals and by the predominating white plagio- 

 clase, which gives the rocks a light colour. In a chemical 

 point of view the rocks from the three districts show such a great 

 conformity, that they must have come from the same magmabasin. 

 å. comparison of the three analyses page 22 will show this. We 

 have here a continuous series from the rock of Svanø to the rock of 

 Bremangerland. 



The rocks deseribed here belong to the granodiorite subfamily 

 of the granit family. The name of granodiorite was first proposed by 

 G. F. Becker who together with H. W. Turner and W. Lindgren 

 during the mapping of Sierra Nevada in California, found an inter- 

 mediate group of rocks, which they would neither call granites nor 

 quartzdiorites. On page 23 we see analyses of these arid other 

 American granodiorites. It seems to me that these rocks are too 



