735 
rite entirely surrounding the lenses of naujaite and increasing 
in number towards the bottom, so that a structure is formed which 
reminds of the “Augenstructur” of some gneisses if this were thought 
many times magnified. Commonly the lujaurites of the breccia-zone 
are black (arfvedsonite-lujaurites), but occasionally —- and this is of 
importance for the genesis — we find also green aegirine-lujaurite, 
bounded on either side by black arfvedsonite-lujaurite, thus proving 
that cifferentiation has taken place. 
The rocks of the lujauritecomplex of Greenland, which is more than 
600 m. thick, are, as a rule, more fine-grained than those of Kola 
and Transvaal and contain a greater quantity of dark constituents. 
Complexes of kakortokites alternate with the lujaurites; these are 
foyaitie rocks, distinguishing themselves from the normal foyaites by 
a greater percentage of dark minerals; they are more coarse-grained 
than the Injaurites, and their average composition corresponds pretty 
well with that of the latter. Light-coloured, red and dark strata al- 
ternate, and it is peculiar that the same succession constantly returns, 
and, in the thickest parts of the complex, repeats itself about forty 
times. As ia the breccia-zone of the lujaurites, the kakortokites likewise 
envelop fragments of naujaite. 
The above-mentioned variations originating from the same parent 
magma are likewise met with among the Transvaal rocks; their 
mutual connection here, however, is more irregular, and can less 
clearly be observed in the field because they are in most places 
covered by other rocks. 
Mechanism of the intrusion of the Pilandsbergen. 
It is peculiar that in the territory of the Pilandsbergen effusive 
rocks are found in large quantity between the deep-seated) whereas 
they do not occur in the surrounding granites and norites. 
It is very likely that, in the Pilandsbergen and its environs origi- 
nally a roof of volcanic rocks has covered the deep-seated rocks, 
because elsewhere in the igneous complex of the Boschveld a thick 
voleanie series still forms the roof of the deep-seated rocks, which 
is intersected by dykes of tinguaitie and camptonitic rocks ®). 
In connection with the intrusion of the foyaitic magma which is 
younger than both the granites and norites, the roof has locally sunk 
1) H. A Brouwer, loc. cit. p. 16. 
2) H. A. Brouwer, loc. cit. p. 35 and 89. 
P. A. Waaner, Note on an interesting dyke intrusion in the upper Water- 
berg system. Transactions Geol. Soc. of South Africa 1912, p. 26 sqq. 
