GEOLOGICAL FORMATIONS. il 
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. as. ; 
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 Kjeringfjeld, to the south of the Sor- 
folden fiord; the micaceous schist encloses beryl. 
On the layers of the taconic period, which have been 
déscribed, 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 graphto- 
lite schist and Orthoceras vaginatum limestone. Above 
