Correspondence — P. W. Stuart- Menteath. 383 



But, after all our labours and strivings to reach the beginning of all 

 things, let us take comfort in this, that, like Pandora of old, we still 

 have Hope left us in the Box (or shall we say in the Rocks ?). 



Those Eozoic rocks which underlie our present oldest fossiliferous 

 strata may yet yield to the geologist and biologist in the future 

 an earlier and more primitive fauna and flora, just as the Lower 

 Cambrian rocks have done for us in the past. 



ooI^I^:^]s:E'Oz^^3D:H]I^^c:E]- 



THE GEOLOGY OF GAVAENIE. 



Sir, — The latest number of the Bulletin cles Services (No. 93) 

 of the French Geological Survey establishes in 300 elaborately 

 illustrated pages a new stratigraphical paradox, confirming those 

 already noticed in your pages. Having mapped the entire district 

 in question on a larger scale some years ago, and having again 

 verified the facts on the spot, I would point out the decisive 

 features recognizable by the practical geologist- 



At Gavarnie the tourist observes a gigantic precipice which is 

 the northern edge of the Secondary and Tertiary sheet that com- 

 poses the Spanish Pyrenees. Its abrupt contact with the PalEeozoic 

 rocks traversed by the entire road of approach, and the consequently 

 sudden opposition between the character of erosion exhibited by 

 the Cirque, excavated in the Secondary rocks, and the very different 

 erosion of the Palaeozoic, is unique in the Pyrenees. 



In the Bull. Soc. Geol. of 1868 I first figured the fault of contact, 

 and I have since traced its outcrop through the Cascade Hotel, the 

 Port de Pail la, the Port Neuf de Pinede, and the Port de Gavarnie. 

 In front of it, the tourist perceives a gigantic wedge of white lime- 

 stones which are visibly continuous with the Devonian limestones 

 of the Palaeozoic valley in which he stands. This wedge forms the 

 Pic Kouge de Pailla, and there contains a lead lode such as abound 

 in the Palaeozoic and are unknown in the Upper Cretaceous of the 

 Pyrenees. Throughout its base, hollow concretions of chert and 

 calcite abound, whose broken sections are easily confounded with 

 Eudists and other shells ; but the only authentic fossil I have found 

 in it was a fairly characterized Atrypa reticularis at a few feet from 

 the fault. The pseudo-fossils have for more than thirty years been 

 mistaken for Eudists such as abound in the glacial blocks abundantly 

 dispersed from the overhanging Secondary precipice. The author in 

 question has accepted the consecrated error, and has inadvertently 

 classed the Palceozoic wedge as a portion of the Secondary that lies 

 beyond the fault. Inevitably, he is hence compelled to class the 

 visible continuance of that wedge to the north as a tongue of 

 Cretaceous extending between the granite base and the remaining 

 Paleeozoic rocks of the French valley. 



His efforts to confirm the initial illusion are ingenious and 

 inevitable. As type of the structui'e he imagines, he selects 

 a section east of Gedre, where he himself admits that the Devonian 

 limestone directly rests upon the granite. At the point he figures 



