Reviews—Dr. Barrois’ Geology of Asturias, etc. Pathe 
connexion with these granites, are seen to traverse the Coal-measures 
(p. 91). The question can only be decided by further examination. 
There is no trace of a single vein of granite penetrating any of the 
Secondary formations, which are so well developed in the Asturias. 
Since, therefore, the Cantabrian Chain is but a continuation of the 
Pyrenees, this fact seems unfavourable to the notion that any of the 
granites in the great frontier chain are even comparatively recent. 
The character of the metamorphism in contact with the granites 
is very similar to what occurs in other areas under similar or 
analogous circumstances.! The Cambrian clay-slates (schists argileux) 
are rendered foliaceous, micaceous, and finally transformed into veri- 
table mica-schists, whilst some banks of schist are charged with 
crystals of garnet. The order of metamorphism is somewhat analo- 
gous to what obtains m Skiddaw Forest. The outer ring consists of 
crumpled schists, the middle ring of macled schists, the inner ring 
of leptynolites. In Skiddaw Forest these three zones of contact 
metamorphism, which has involved the Graptolite-bearing beds of 
the second fauna, are represehted from without inwards by the 
Chiastolite Slate, containing Trilobites and Graptolites, secondly by 
the Spotted Schist, finally by the Micaceous Schist. 
The author carefully traces the order of these changes. First, 
there is an alteration of structure without any fresh mineral com- 
binations of importance, but the carbonaceous matter and the limonite 
tend to pass into graphite and magnetite. Secondly, there is a sub- 
stitution of a brownish biotite for the hydrated green silicate which 
envelopes the quartz grains of the less altered rock: at the same 
time, there is a more decided development of chiastolite and 
andalusite. Thirdly, the andalusite schists become more and more 
micaceous on approaching the granitic mass, but still there are no 
felspars. 
He argues that the granite has not generally effected any material 
change of substance, since the fluorine and titanium minerals occur 
alike in the unaltered argillaceous schists, and in the macled schists. 
The excess of alumina has gone to form andalusite in distinct crystals, 
which envelope in their formation the older minerals of the rock, such 
as graphite, tourmaline, rutile. The absence of these minerals in 
the intercalated grits is worthy of remark. 
Metamorphism of this kind, then, consists in a series of molecular 
changes, diminishing irregularly in intensity on receding from the 
centre of promotion. Such chemical changes as have taken place 
consist, Dr. Barrois thinks, in a loss of constitutional water and 
carbonaceous matter and a gain in silica. This is also the conclusion, 
he tells us, at which Fuchs and Rosenbusch arrived with regard to 
the metamorphic schists of the Pyrenees and the Vosges. We 
should rather like to see some further confirmation of this view, viz. 
that an increase of silica in the beds accompanies the genesis of the 
sub-silicate, andalusite. Moreover, it is contrary to the analyses 
1 Tt should be noted that both these granites contain black mica, and both produce 
contact metamorphism. Those granites which contain no other than white mica are 
said to produce no contact metamorphism. 
