Vol. 60.] ANNIVERSARY ADDRESS. lxi 



Charles de la Yallee-Poussin, he wrote the important monograph on 

 the mineralogical and stratigraphical characters of the rocks called 

 ' plutonic' in Belgium and the French Ardennes, which was presented 

 to the Belgian Academy in 1874, and appears among the * Memoires 

 Couronne's ' of that institution. From that time onward he continued 

 to give to the world other papers on Belgian rocks, among them an 

 interesting account of the minute structure and mineralogical com- 

 position of the whetslates, which he showed to abound in garnets. 

 He described likewise the phthanites of the Carboniferous Limestone, 

 and pointed out the distinctive characters of the calcite and dolomit-e 

 in the same formation. But the most notable of these contributions 

 to the geology and petrography of his native country were those in 

 which he discussed the phenomena of regional metamorphism, as 

 exhibited by the phyllades and the garnetiferous and amphibolitic 

 rocks. Confirming the general accuracy of the previous observa- 

 tions of Duniont, he regarded the distinct metamorphism of that 

 region as the result of intense mechanical disturbance, with accom- 

 panying chemical and mineralogical re-arrangements. In recent 

 years, having widened his experience of the problems of metamor- 

 phism. he was inclined to question the validity of his earlier 

 conclusions, and was rather disposed to think that the alteration 

 of the rocks might be due really to contact-metamorphism, though 

 the invading igneous material had not yet made its appearance 

 at the surface during the prolonged denudation of the rocks. 

 Prof. Gosselet, whose great work on the Ardennes marks him 

 out as the chief authority on the geology of that region, strongly 

 opposed this change of opinion, and contended for the essential 

 accuracy of the earlier deduction. 



Renard's published papers at once attracted attention, both among 

 petrographers and stratigraphers. They showed him to be a 

 capable chemist, and at the same time to have acquired a command 

 of all the most modern resources of investigation with the micro- 

 scope. But they further proved that he was no mere worker in a 

 laboratory or museum, for they evinced that he had accustomed 

 himself to study the rocks in the field, to examine their strati- 

 graphical relations, and to take broad and enlightened views 

 regarding their origin and history. His writings had gained 

 so much approbation hi this country, that when the various 

 treasures brought home by the CJiaUenger-Exipedition were par- 

 titioned among recognized experts for determination and de- 

 scription, the petrographical specimens were entrusted without 



