384 Correspondence — P. W. Stuart- Menteath. . 



there is a thin intercalation of Silurian, but only the white and 

 fissile surface of the granite can be mistaken for any independent 

 limestone. That granulitic surface has certainly misled him in his 

 sections of Heas ; and in general he has taken for a regular outcrop 

 of limestone the very regular band of fallen and glacial blocks 

 which skirts the steep talus of the Silurian schist at. the foot of the 

 precipices of Devonian limestone. Among these chaotic blocks 

 I have found no Eudists in place, but plenty in transported 

 fragments. At the end of the Estaube valley the confusion is 

 repeated between the Secondary precipice and the Palgeozoic wedge, 

 here limited by a friction breccia. 



In following a phantasm, the author has ignored the fact that the 

 limestone he classes as Cretaceous descends abruptly in thin sheets 

 both at the bridge of Gavarnie and at two kilometres to the south of 

 it, these sheets being pinched between the granite to a depth beneath 

 the floor of the valley. Strongly metamorphosed and visibly inter- 

 sected by granite veins, these sheets prove that the granite was both 

 active and flexible after the deposition of the supposed Cretaceous. 

 At Bareilles the author has figured as a limited projection a third 

 similar sheet. Here I formerly described, as undoubtedly in place, 

 circular sections which I compared to the Jurassic corals I had 

 found at the Col de I'Espandels, west of Argeles. But the author 

 himself figures the limestone of the Col in question as Devonian, 

 and I have ascertained that the apparent fossils of Bareilles are 

 mere sections of pipes and other concretions of calcite. 



The paradox in question hence arises from common illusions and 

 the existing obstacles to their discussion. It is also an attempt to 

 justify and excuse the former classification of the dalle limestone as 

 Cambrian, because beneath the Silurian. In view of the fact that 

 the official map of 1890 is proved entirely wrong by the new 

 survey here in question, it should be remembered that the said map 

 was in entire defiance of local observation. 



Between the present paradox and the case of Eaux Chaudes an 

 analogy is suggested by ignoring the fact that the fossils are there 

 both specifically determinable and visibly in place ; and the further 

 fact that the Cretaceous there penetrates, vertically or reversed, from 

 the surface, and accompanied by numerous ophites along its contact 

 with the PalEeozoic. At Gavarnie the fossils are worthless, the 

 stratigraphy figured is in contradiction to salient facts, and the 

 resulting paradox is itself an indication of the erroneous observation 

 demonstrable on the spot. The relations of the Secondary, as 

 followed by the Spanish geologists and by myself to the Pic d'Anie 

 and the Maladetta, are in flat contradiction to what is here imagined. 

 It is unfortunate that the work in question ignores those relations 

 on every side. Even in the only other inclusion of Secondary rocks 

 figured and described, the author entirely ignores the presence of 

 the extensive bands of ophite by which it is limited between Argeles 

 and Arbeost. Supposed " fragments of the tests of Eudists " are 

 only valuable when confirmed by unquestionable fossils or by 

 stratigraphic identification with adjoining fossiliferous bands. 



Cautebets, July 18, 1903. P. W. Stuaet-MenteatH. 



