E. E. L. Dixon — The Gavarnie Ocerthrust. 409 



3. Cretaceous (Campanian). Rubbly, thick-bedded, partly dolomitic, 

 white limestone with hippurites, etc., the base, which contains many 

 angular quartz-fragments, showing no signs of disturbance. 



2. Permo-Trias. Chiefly micaceous shales, red on the whole, but 

 partly changed to buff and green at the top; also some fine-grained 

 sandstones, and, at the base, several feet of quartzitic sandstones and 

 conglomerates of subangular quartz-fragments. Total, about 50 feet. 



1. Basement-platform. Granite and mica-schist, worn down to an 

 even surface to which Permo-Trias and Campanian are parallel, both 

 as a whole and in individual beds. 



Carez, in discussing the relations of the Campanian to underlying 

 rocks, does not refer to the fact that on the Spanish side it is underlain 

 by Permo-Trias, and consequently does not consider the relations of 

 these two, but it is a necessary consequence of his theory that the 

 former should be regarded as thrust over the latter. But here the 

 rocks immediately beneath the supposed overthrust do not form a rigid 

 platform as in the cases considered by Carez, where their abrupt 

 truncation lent colour to his supposition ; on the contrary, they consist 

 of soft beds on which the limestones rest with apparent conformity, 

 and, although the one group would be much less rigid than the other 

 under the influence of lateral pressure, neither shows any sign of 

 differential movement either within itself or relatively to the other. 

 Also, the fact that the basement-platform of crystalline rocks passes 

 beneath the Permo-Trias shows that it has not been planed down by 

 an overthrust, as there is no evidence of such movement of the beds 

 which are there resting on it. 



In view of these facts and their bearing on Carez' arguments, we 

 have concluded that the Cretaceous in the neighbourhood of Gavarnie 

 has not been overthrust. The same is probably true of the Cretaceous 

 elsewhere in the same region, for it is on the strength of the evidence 

 already discussed that Carez relies largely when he says, " Le Cretace 

 superieur de Gavarnie, du Bala'itous, des Eaux-Bonnes et du pic 

 Bazes n'est pas en place, et ces lambeaux sent les restes d'une 

 immense nappe de charriage venue du Sud et qui se montre . . . 

 depuis Eugui jusqu'au rio Flamisel, sur une largeur de plus de 

 200 kilometres." (Eugui and the river Flamisel are, respectively, 

 far to the west and east of Gavarnie.) As Gavarnie lies nearest the 

 roots of this supposed overthrust and at about the middle of its length, 

 the undisturbed state, in places, of the Cretaceous there, appears to us 

 to invalidate Carez' overthrust, and with it Termier's conclusion, 

 based on Carez', that the whole Cretaceous of the Pyrenees has been 

 ' carted ' from the south. It appears, therefore, that a very useful 

 service has been performed by Mr. Stuart-Menteath in protesting 

 against the wholesale invocation of charriages if they are supported by 

 no better evidence than in this instance. 



The third problem we shall discuss relates to the age of the 

 crystalline rocks of the basement-platform below the Cretaceous 

 in the Gavarnie (Pau) and Heas valleys, and is of more than local 

 interest as it raises the old question whether gneisses and schists, to 

 all appearance Archaean, mav in reality be Palaeozoic or even younger. 



The rocks consist of mica- and quartz-schists, containing an 



