68 MISS C. A. HAISIN 02? CEETAIN [Feb. I9OI, 



expressly says that the corneite is not found only in this position 

 (op. cit. p. 771). Thus it seems more probably a coincidence, than 

 a relation of cause and effect. 



If the metamorphism of the ' corneite ' were due to these causes, 

 how could it be intercalated among grits which are not much meta- 

 morphosed (as at Serpont, etc.)? 



It is difficult to understand how the movements which produce 

 such undulations as are figured (op. cit. p. 769, fig. 208) could have 

 caused the formation of the secondary minerals. These are often 

 well-defined crystals, while in other districts far greater compression 

 and folding has resulted only in microlithic development. 



Even in the Ardennes, strata which are much more intensely 

 contorted do not show any marked metamorphism. 



No explanation is offered as to how pressure could have caused 

 the metamorphism of ' nodules ' or *" nodular patches ' (op. cit. 

 pp. 769, 789 & figs. 208, 216, etc.). 



Prof. Gosselet refers the moi^e marked metamorphism to move- 

 ments of five different kinds : — (a) anticlinal, (5) synclinal, (c) near 

 the sides of a fault, (d) along a fault, and (e) gliding-planes. But 

 there can hardly be any locality here which does not exhibit one 

 (or generally more) of these disturbances. Yet the chief secondary 

 minerals are limited in their distribution. 



AVhen we consider what causes may have acted in the district, it 

 is clear that the alterations include successive phases, one at least 

 of which was due to pressure. Doubtless, as maintained by Dumont 

 and by Prof. Gosselet, the pressure was of more than one epoch. 



The altered rocks, so far as I have studied them, may be 

 grouped as : — 



1. Crushed quartzose grits (' artose porpbyrique '), with micromineralogical 



development (as, fur example, Lamersdorf, Salm Chateau). 



2. Rocks containing ilmenite, biotite, ottrelite, chlorite, with recrystallization 



of quartz. All tltese minerals are found over wide areas. 

 3.' Garnetiferous and bornblendic rocks in limited patches. 



Of these, the first and some of the second ojroup doubtless exhibit 

 pressure- effects, including possibly the development of ilmenite and 

 of otirelite; while the chlorite may be derived from biotite, or 

 indirectly from hornblende. 



Other results, such as the development of biotite ; the recrystal- 

 lization of quartz and felspar ; and, even more important, the 

 development of chiastolite described by M. Dupont, show such 

 resemblance to the effects of somewhat slight contact-metamorphism 

 that they are probably due to au igneous mass coming near to the 

 surface in certain areas. We may compare the rocks with some of 

 those from Andlau, or more closely with those from New Galloway 

 collected by the late Samuel Allport.^ In the latter, even in the less 



1 I have to thank Mr. L. Fletcher, MA., F.R.S., and Mr. G. T. Prior, M.A., 

 of the British Museum (JN^aturai History), for allowing me to examine and 

 compare the slides of these rocks. 



