329 
at about the same time. Ramsay regarded the lujavrites as 
making up ‘the upper portion of a laccolite !. But this view 
is mainly inferred from the structure of the rock, for at Lujavr- 
Urt no remnants of the cover of the ‘laccolite’ has escaped de- 
struction, and there is no indication that the lujavrite has been 
covered directly by the country rock. On the other hand, the 
presence of some remnants of coarse-grained tavite in the 
upper portions of the mass suggests that, as is still the case 
with the Greenlandic lujavrite, the Kola lujavrite may origin- 
ally have been overlain by similar coarse-grained abyssal rocks. 
At Ilimausak the geological position of the lujavrite is 
clear. (1) It is the lowest visible rock of a batholite whose 
upper part consists of very coarse-grained naujaite, foyaite, 
syenite, and granite, and these rocks already occupied their 
present position when the lujavrite solidified. The lujavrite, thus, 
has consolidated in a situation more abyssal than that of the 
granite. (2) The total mass of the lujavrite exceeds that of all 
the other nepheline-syenites of this batholite put together (the 
volume of lujavrite at Lujavr-Urt is perhaps still greater). (3) At 
the junction with the wall rock the lujavrite exhibits a contact 
modification quite analogous to the junctions of ordinary abyssal 
rocks (see p. 176). 
We must, therefore, conclude that the lujavrite, in spite 
of its fine-grained and schistose structure, is a true abyssal 
rock. 
1 Fennia XJ, no. 2, 1894, р. 97. The laccolitic nature of the Kola ne- 
pheline-syenites, suggested by Ramsay in this important memoir, is a 
matter of inference as no bottoms to the laccolites have been observed. 
The assumption is based mainly upon the observation of stratified rocks 
which have been found locally at the margin of the nepheline-syenites. 
These stratified rocks dip towards the Plutonic mass and are, partly, 
covered by it. The conditions apparently are analogous to those de- 
scribed in the present report as occurring at Mount Iganek (see Fig. 21, 
p. 252) and at several other places. 
“Dafür spricht in erster Linie die Structur der Lujavrite” loc. cit. 
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