Review of Recent Geological Literature. 129 
This intrusion, covering some 40 km'., is regarded as younger 
than the anorthosyte since it has compressed and produced parallel 
structure in that rock along the contact. The interval between the two 
eruptions is thought to have been so short that the anorthosyte was not 
fully congealed, so that the compression of the later intrusion produced 
parallel structure in the former and at the same time the hot anortho- 
syte caused very slow cooling of the Birkrem laccolith, thus giving 
opportunity for the great amount of differentiation which it exhibits. 
The granite (analysis VII of the table) is an interesting type of 
soda granite not heretofore described. It consists of 74 per cent, feld- 
spar, 1.61 per cent, hypersthene, 0.51 per cent, ilmenite and 24.05 per 
cent, quartz, the feldspar being almost wholly microperthite of the 
■composition Orj (AbrAni)-.4. 
The Lister Adamellyte Area. This covers no km". The rock is 
quite homogeneous throughout though reaching the basicity of bana- 
tyte in peripheral portions. The lack of differentiation is explained 
"by the supposition that the enclosing rocks were cold at the time of 
the intrusion, and that erosion has been deeper than at Birkrem. The 
rock is very similar to the acid rocks at Birkrem, differing mainly in 
the proportion between lime and magnesia and the alkalies (analyses 
VI and VII) so that the microperthite has the composition Ori (Ab4.r. 
An04... 
The Banatyte Area east of Farsund. These rocks are reddish and 
coarse grained, consist of hornblende, reddish feldspar and quartz and 
have heretofore been called hornblende granites. But the rock is too 
low in silica and too high in lime (analysis V) to be classed with the 
granites, and must be put in the orthoclase-plagioclase group on 
account of the large content of the latter mineral. Peripherally it 
becomes more basic and belongs with monzonyte (see analysis IV). 
The Dike Rocks of the District. Dikes are not particularly abun- 
dant but are important, and noteworthy on account of their great 
length. Dikes of anorthosyte, anorthosyte noryte, noryte, gabbro 
noryte, quartz noryte. monzonyte, augite granite, banatyte, aplyte and 
diabase occur, mentioned in order of age, the diabases being the 
youngest. The larger number are of closely the same age as the cor- 
responding intrusive masses. The comparative age of the granite, 
aplyte and diabase dikes is uncertain. 
Sequence of Eruptions in the District. All the rocks are regarded 
as differentiation products of a single magma, whose composition is 
calculated from the areal extent of the various types, a somewhat 
venturesome proceeding, though not without value. The conclusions 
in regard to relative age are based on the dikes and the phenomena 
at the junctions of the different intrusions. The anorthosyte was first 
intruded. The Rekefjord and Hitteren Island quartz noryte masses 
followed before the anorthosyte was fully congealed, as did the 
Hcaskestad monzonyte, whose relations to the quartz noryte cannot 
'be determined. 
The Birkrem laccolith with its adamellyte and granite is younger 
