Correspondence — P. W. Stuart- Menteath. 523 



branches. Whether geologist, palaeontologist, mineralogist, petrologist, 

 or mining expert, no one who pretends to do any work can afford to 

 be without this publication, which, despite the faults of omission or 

 commission usual in any work of the kind, is far and away the most 

 valuable of any geological bibliography offered to the public. 



The singular thing is that it should still remain unknown to many 

 at home and abroad, for its low price (2s.) places it within reach of 

 all. But as no attempt is made by the Society to advertise its 

 existence, perhaps this is not to be wondered at. Some people seem 

 to think that it is limited in its scope to those items received by the 

 Geological Society ; so it is, but the Society receives over 80 per cent, 

 of the publications on the sciences it includes. The extraordinary 

 value of the book lies in its index. Take one entry — " C. Eeid, on 

 the Geology of the country round Newquay, Mem. Geol. Survey, 

 1907." This is indexed under no less than fourteen heads, so that 

 practically the whole contents of the memoir can be picked up under 

 any special item. The same minuteness of indexing applies to the 

 foreign literature. 



It is undoubtedly the most valuable publication issued by the 

 Geological Society of London, and will remain a standard work of 

 reference as long as any geologist worthy the name interests himself 

 in the subject. 



C0E,I?,ES:E>03SriDEIsrCE. 



THE GAVARNIE PEOBLEM. 



Sir, — Having only now seen Mr. Dixon's sections and con- 

 clusions, I can supplement them from observations repeated during 

 the present year. 



On Mr. Dixon's map the essentially continuous sheet of Hippurite 

 limestone is figured as absent over two spaces each a kilometre in 

 extent, and definable as the most easily accessible from Gavarnie. 

 One of these is concealed by talus, but that at the mouth of the 

 Ossoue A^alley gave me, in 1894, the following results of field and 

 microscopic observation, repeatedly verified since that date. The 

 supposed break is merely an extremely metamorphosed portion of the 

 visibly continuous Cretaceous. It is penetrated throughout by 

 numerous veins and bosses of microgranulite, undeniably proceeding 

 from the underlying granitic basis. M. Bresson first admitted it to 

 be pinched Cretaceous, but is now compelled to describe it as Palaeozoic 

 " by analogy of facies and by the established data of the age of granite." 

 This analogy and these data led the last Director of the French 

 Survey to map the Hippurite limestone as Cambrian over half the 

 Pyrenees, and to denounce my maps and observations as "■ a priori 

 inexact." Even M. Carez, M. Lacroix, and M. L. Bertrand admit 

 them to be baseless. But M, Bresson is similarly compelled to figure 

 the Caprina Cenomanien as Aptien at Sarrencolin and the Ordovician 

 at Bagneres de Bigorre as Permian, and to describe the Cambrian of 

 Jacquot as a masterly definition of the Devonian, although it was 



