96 



and resulting from the alteration of siliomagnesian sediments, and in 

 many writings since has supported this view of the subject. In the 

 transactions of the Royal Society of Canada, "Vol. I, Sec. IV., 1883, is 

 given the geological history of serpentines, including studies ot Pre- 

 Cambrian rocks by this author. Very interesting facts and many 

 observations from several European and American geologists are men- 

 tioned in this cleai-ly written paper, the most of which are in support 

 of the theory therein advanced. Some of the serpentines that were 

 then declared to be indigenous have been studied more in detail, and 

 facts of recent date, brought to view, tend to show that these ar6 in 

 certain places eruptive. 



The serpentines are, as we all know, metamorphic or igneous 

 rocks, and consequently we should not judge of their age from lithological 

 evidence only, for with very few exceptions this criterion is of little 

 value. Since it is generally admitted that metamorphic rocks are not 

 of any particular geological age, so we shall have to consider our ser- 

 pentines as being also of different ages, for they not only differ in their 

 lithological association but in chemical composition as well. 



If we have serpentines that are the altered remains of olivine 

 rocks, we have them derived from some other source as well, for it is 

 impossible to suppose that the banded and slaty serpentines of the 

 Shickshock mountains in Gaspe, and of Long Lake in the Province of 

 Quebec are due to the metaniorphism of the same class of stratified 

 beds, the main constituents of which are derived from the trituration of 

 olivine rocks ; for in that case they would occur in some characteristic 

 bands, and this is not the case as far as we know. 



There is a magnesian rock says Daubree that is very closely allied 

 to peridotite and therzolite although it presents a great many peculiari- 

 ties which are not characteristic of these. Although serpentine is 

 hydrated, infusible and without distinct crystallisation, it occurs with 

 eruptive rocks, and the general view of geologists is that it is derived 

 in many cases from peridotite, since it exhibits very often the charac- 

 teristic form of crystals of that rock. 



By his synthetic studies, Daubree has discovered that very often 

 serpentine has a tendency to change to a peridotite and he is of the 

 opinion that it is derived from the hydration of olivine rocks. There 





