FIELD OBSERVATIONS IN NORTHERN NORWAY Asal 
be made. The amphibolites might be somewhat older than the 
Raana norites and accordingly have been subject to a longer period 
of dynamic metamorphism during the Caledonian folding. But 
the reason for the different degree of metamorphism might also be 
that the process has been able to act more severely upon these 
rocks on account of their lesser thickness and their very intimate 
injection in the surrounding schists—which show about the same 
degree of metamorphism—while the massives of the Raana type 
have resisted better. 
The mineral composition of the ordinary amphibolites is: 
amphibole and acid plagioclase as the predominant minerals, more 
or less epidote or clinozoisite, quartz, leucoxene, and often garnet 
and biotite. None of the primary minerals are left. 
The original basic plagioclase has been more or less Arbitized 
producing plagioclases from albite to oligoclase composition, while 
part of the lime enters the epidote minerals. The original pyrox- 
enes have been changed to amphibole, and it is noteworthy that 
while in the Raana field the uralitization has produced a nearly 
colorless amphibole of actinolitic composition, poor in aluminia, 
the metamorphic rocks contain common green amphibole, rich 
in aluminia. 
The differentiation shows Ueeee features analogous to those 
just described from the Raana field, but also significant differences. 
In many of the amphibolite zones we find a number of small 
bosses of serpentine rocks, very irregularly distributed. The 
dozens of such bosses observed nearly always occur within the 
amphibolite rock and are not separately injected into the schists. 
They are all of relatively small dimensions, rounded or lens-shaped, 
and sharply.defined from the surrounding amphibolite. They 
obviously correspond to the peridotitic rocks of the Raana field, 
but are always completely metamorphosed to serpentine and talc 
minerals. 
In numerous cases the amphibolite itself is nearly homogeneous, 
and without intermediate steps there is a wide gap over to soda-rich 
granites which occur nearly everywhere in intimate connection 
with the amphibolite series in such a way that there can be no 
doubt of their mutual relation as differentiation products. 
