GEOLOGICAL FORMATIONS. Ill 



Above this layer, in some mountainous region, is found 

 the third, known as high mountain quartz, with transition 

 schists, and beds of dolomite and gneissic schists. The 

 high mountain quartz is sterile and poor. 



These layers are in many places traversed by great 

 subsequent eruptions of gabbro [basalt?], of which are 

 formed a multitude of mountain summits and plateaux. 

 The rock thus produced is composed mainly of granite, 

 syenite, and greenstone, and metaliferous minerals are 

 found collected in many places on the confines of this 

 rock. On the Dovrefjeld are found more recent eruptions 

 of trap. 



The schistose and limestone region, along the limits of 

 the wall of exterior granite, manifests transformation in a 

 way perfectly evident. Their broken or inclined beds 

 seem metamorphosed, each according to its primitive 

 nature, in a manner analogous to what may be seen in 

 the comparatively much more accessible and more explored 

 silurian region of the Christiania fiord. The calcareous 

 stones have crystallised into marble, the argillaceous 

 schists and the sandstones have become schists of mica- 

 ceous gneiss. Garnet is often found developed in the 

 schists ; and at the Kjaeringfjeld, to the south -of the Sor- 

 folden fiord, the micaceous schist encloses beryl. 



On the layers of the taconic period, which have been 

 described, there rest in Southern Norway silurian forma- 

 tions disposed in many layers, and finally layers of sand- 

 stone and conglomerate, corresponding to the Devonian 

 formations. 



In some places the second layer of the taconic formation 

 the dicytonema schists and olenus limestone supports 

 thick layers of gray, impure limestone, alternating at 

 times with dark, argilaceous schist. The limestone encloses 

 a quantity of fossil trilobites, especially species of the 

 genus Asaphe, Orthoceras vaginatum, belonging to the 

 cephalopods, and graphtolites, a species of polypes. From 

 these fossils it has received the name of ancient graph to- 

 lite schist and Orthoceras vaginatum limestone. Above 



