p. W. 8tuart-Menteath—0n the Pyrenees. 355 



preventing the publication of the details which the most experienced 

 geologists of the Pyrenees have been long accumulating regarding 

 the real structure of the most typical and best exposed mountain 

 chain in Europe. Before even the most salient facts of that chain 

 have been permitted to appear in the ordinary and essential channels 

 of geological documentation, a theory of mountain structure derived 

 from the elaborate compilation of Suess has been made the criterion 

 of fact and based upon the selected errors of writers who have 

 obtained, on various pretexts, portions of the work of practical 

 geologists in the Pyrenees. The entire opportunity of verification 

 afforded by the Congress has been subordinated to the interests 

 concerned. International co-operation in such matters may only 

 tend to confirm attempts to override observation, and to silence 

 those who have acquired the long preliminary practice required to 

 correct the illusory and perspective impressions of mountain structure. 

 Parisian geologists apparently fail to realize the inconvenience of 

 vast innovations in maps whose freedom from theoretic conjecture 

 has frequently cost the sacrifices of a lifetime. 



In the superficial geology of the Gavarnie valley the Congress 

 was equally misled. In 1866 I proved, in the Bulletin Societe 

 Ramond, that the conglomerate of the Park of Pau, previously 

 described by Charles Martins and others as a moraine of the Glacial 

 Period, was situated at sixteen kilometres outside of the extreme 

 limit of the moraines of that period, and that it represented the 

 Oligocene ice of the Superga of Turin, with which I was familiar. 

 Charles Martins hastened to correct his conclusions ; but, assuming 

 the opposite extreme in a theoretical map of the glacier of Gavarnie, 

 placed the upper limit of that glacier at fully 1,000 feet below the 

 distinct lateral moraines which can be seen to the north of Argeles 

 by any observer who will climb the mountains. In the Bull. Soc. 

 Geol, 1868, p. 697, I figured a great fault at Gavarnie, which had 

 been overlooked by Dufrenoy. This was adopted by Magnan, and 

 generalized into a system which has long misled observation. 

 At Gavarnie that fault juxtaposes a character of erosion which is 

 common on the Spanish side, in abrupt contrast with the very 

 different character which prevails in the French Pyrenees. The 

 Gavarnie valley, in receding rapidly through the greater erosion 

 on the moist and snowy French slope, has abruptly entered the 

 Cretaceous and Tertiary sheet of the Spanish side. The same 

 circumstance accounts for the peculiar scenery of other Pyrenean 

 valleys, but at Gavarnie it is accentuated by the prominence of 

 the fault and the considerable drainage of the lofty Mont Perdu. 

 It is unfortunate that personal questions should prevent, at every 

 point, the clear recognition of the facts of Pyrenean geology, owing 

 to the manner in which their history has been altered in Paris in 

 defiance of both documents and dates. The briefest statement of 

 observations might have removed difficulties that have hampered 

 progress for thirty years, had such statement not been rendered 

 obnoxious by previous misrepresentations which it is impolite to 

 notice and unpleasant to explain. In welcome confirmation of 



