FIELD OBSERVATIONS IN NORTHERN NORWAY 703 
very strong throughout the region, producing garnet-mica schists, 
marbles, quartzites, etc., but generally not with the development 
of lime-silicate minerals. 
In this region there has not been disclosed any unconformity 
or discontinuity in the sedimentation. 
During the Caledonian folding this series was intruded by great 
masses of eruptive rocks, especially in the axial part of the chain. 
Most of these are ordinary granites. 
There also occur in considerable quantities femic eruptives, 
very intimately intruded in the schists, and like these thoroughly 
metamorphosed to amphibolites and different eruptive gneisses. 
_ They are much differentiated, the last products generally being 
soda-rich granites (or Trondhjemites). 
Moreover, we find as isolated fields more extensive areas of 
gabbroidic eruptives, less metamorphosed, sometimes nearly fresh. 
They were also intruded during the Caledonian folding period and 
are chemically nearly associated with the former group, from which 
they do not differ very much, if at all, in age. They also show 
marked differentiation and on account of their relative freshness 
afford very interesting petrographical material. 
All the eruptives seem to belong to the same cycle of orogenic 
intrusions. Original lavas or tuffs, which occur in great masses in 
the Trondhjem district farther south, have not yet been identified 
among them. 
The intrusions have everywhere occurred under a heavy load 
of sediments, and the whole complex must have been heated to a 
considerable temperature. 
Outside the real root of the mountain chain all eruptives seem 
to have been intruded completely parallel to the schists. Espe- 
cially in the district to be considered here, we nowhere find crossing 
eruptive dikes or other eruptive bodies cutting the schistosity 
(excepting the pegmatite dikes). It seems to have been a general 
rule that the magmas, after intrusion, were subject to magmatic 
migration between heated schists, from the root of the mountain 
chain outward. In this way the magmas may have wandered for 
very considerable distances from the places where they broke into 
the schists, until they came to rest. The moving force was induced 
