762 REVIEWS 
evidence for clearly defined endomorphic action leading to serious 
modification of eruptive magmas is, in many cases, due to a removal of 
the mixed zone of assimilation from contacts by bodily movement of 
the magma. Such a period of active assimilation and removal is fol- 
lowed by another of limited or no power of assimilation, during incip- 
ient cooling, and that stage by a third marked by the crystallization of 
essentially pure magma in contact with country rock, perhaps meta- 
morphosed but not incorporated. 
3. A striking argument for the modification of the granitite in this 
manner is afforded by certain inclusions within it, described as sur- 
rounded by the hornblendic basic types identical with those character- 
izing the main contacts. 
4. No independent dikes, apophyses, or stocks of the basic rocks 
occur in the region, and on the right bank of the Oriége, at least, there 
is no dynamic action sufficiently intense to explain the presence of 
diorites, etc., in the granitite by any system of cross-faults. 
5. Lastly, the absence of chilling phenomena in the stock, the 
intensity of the exomorphic metamorphism, the enormous number of 
apophyses in the slates, as well as other facts, all tend to show a 
condition of high temperatures for a long period, and of abundant 
mineralizers which are permissive of the large amount of recrystalliza- 
tion necessary to explain the occurrence of the basic rocks. 
The mode of intrusion is implied in what precedes—a muse en 
place by progressive assimilation of the overlying terranes. The 
proofs of absorption of the quartzites and slates are not so strikingly 
manifest as those in the case of the limestone, but they are regarded 
by M. Lacroix as equally valid. On the other hand, neither block- 
faulting, nor the batholithic, nor the laccolithic hypothesis seems to be 
admissible. 
On the whole, the memoir is seen to have its chief importance in 
upholding first, the doctrine of feldspathization of the metamorphic 
aureole about an intruded granite by the addition, in the presence of 
mineralizers, of feldspathic material from the granite’s own mass ; sec- 
ondly, the doctrine of assimilation ; and, lastly, the theory of the mzse 
en place of intrusive granites, as enunciated by M. Michel Lévy. It is 
safe to say that, from the point of view of field observations and of 
comparative mineralogical study, these tenets of the French school of 
petrographers have never had in a single locality such strong confirma- 
tion. We shall look forward with interest to the forthcoming memoir 
