1890.] GEOLOGISKE IAGTTAGELSEE FKA TRONDHJEMS STIFT. 57 



III. The environs of Trondhjem. 



One of the most remarkable features nere is the grairite 

 (dotted on the map p. 6) just west of the town. The granite 

 is of middling size of gram and besides biotite contains some 

 greenish fine-shelled sericitic coustituent; on account of this it 

 has earlier often been called protogine-granite. Besides the 

 massive variety there is one with a plane parallel structure in 

 appearance much resembling gneiss with thick eleavage; the 

 typic granite may in certain flakes, having a thickness of 3 to 

 10 or more m. by degrees go over to a rock having a thin 

 eleavage and resembling gneiss or even mica-schist. The schistose 

 granite. partly also the massive rock, is penetrated by a system 

 of cracks. Both the latter and the plane parallel structure 

 dip 20° to 30° E. When both the system of cracks and the 

 plane parallel structure are seen at once the latter seems to dip 

 rather less than the former. Sometimes stretching structure 

 dipping in an easterly direction may be seen at the same time. 

 In the gneissose variety of the granite the quartz has some- 

 times a tendency to occur porphyritically as eyes; a quartz-eye 

 gneiss is thus produced. 



Raised beaches are depicted p. 25. 



IV. Excursion from the railway station Eidet to the Sylene 

 mountain group on the border of Sweden and thence to 

 the station Heimdal. 



The map p. 28 gives a view of the district in question. 

 The names of several of the groups of rocks proposed by Kjerulf 

 are given on the map. The greater part of this section will 

 chiefly be of interest only to afford supplementary information 

 to the works of Hauan, Horbye, Kjerulf, Keilhau and Naumann 

 (Literature p. 31, 34. 37). We shall only mention a few details. 



