xliv PEOCEEDINGS OF THE GEOLOGUCAL SOCIETX. [vol. Ixxiii, 



AWAED OF THE WOLLASTON MeDAL. 



In handing the WoUaston Medal, awarded to Prof. Antoijs^e 

 FEANgois Alfeed Laceotx, F.M.Gr.S., to Sir Aechibald Geikie, 

 O.M., for transmission to the recipient, the Peesident addressed 

 him as follows : — 



Sir Aechibald Geikie, — 



For a Medal instituted ' to j^i'omote researches concerning the 

 mineral structure of the Earth,' it would be difficult to find a fitter 

 recipient than Prof. Lacroix, to whose labours in the domain of 

 Mineralogy and Petrology our science is so deeply indebted. 

 His researches on the optical and cr3''stallographic constants of 

 numerous minerals have given us a mass of useful data ; but it has 

 always been his practice to extend his investigations to the field as 

 well as to the laboratorj'". His studies of the mode of occui'rence, 

 the mutual associations, and the manner of origin of a host of 

 species have done much to rehabilitate Mineralogy as, not merely 

 a department of Physics and Chemistry, but a fascinating branch 

 of Natural History. His many separate papers deal with material 

 from all parts of the world ; but of chief importance will always 

 be reckoned his four volumes on the Mineralogy of France and her 

 Colonies, a single-handed work unique in its wide scope and com- 

 prehensive treatment. 



In Petrology, too, Prof. Lacroix's contributions have been 

 numerous and many-sided. Of special note for their influence 

 upon the science are his i-esearches on contact-metamorphism, 

 contained in the Bulletins of the Geological Survey of France, his 

 various memoirs treating of the inclusions in igneous rocks, and 

 his comparative study of the volcanic products of Mont Pele, 

 followed by a like examination of the rocks of Vesuvius. 



From the products of volcanoes to the physics of volcanic action 

 is a natuml transition, and in respect of both Prof. Lacroix's 

 mission to Martinique in 1902 was eminent^ fruitful in results. 

 In particular, he was able to elucidate two remarkable phenomena 

 previously unrecognized or unappreciated : the peculiar plugs or 

 domes formed under certain conditions by extruded lavas, and that 

 most terrible of all volcanic effects — the nuee ardente. 



As a diligent student of his writings, I feel a special pleasm*e 

 in placing the Wollaston Medal in your hands for transmission 



