266 P. Tf^, 8tuart-Menteath—Sult DejwsiU of Dax, etc. 



■which closely resemble those of the Trias formation. A classical 

 investigation of the Iceland springs, by Bunsen, proves that such 

 variegated marls are in active production beside volcanic rocks at 

 the present day. And beside the Baignots establishment at Dax 

 a limestone containing fossils of the Upper Chalk is transformed ta 

 dolomite and traversed by the hot springs. But although the 

 springs can furnish by their constituents and effects a satisfactory 

 explanation of both the salt and all its accompaniments of Triassifr 

 fades, it would be rash to ignore the splendid investigations of 

 Ochsenius on the relations of sea-water to salt deposits throughout 

 the world. Wherever and whenever I have heard the Triassic 

 theory of Pyrenean salt expounded by its foremost representatives, 

 they have ignoi'ed such helpful assistance. It is therefore useless 

 to urge their attention to the fact that either the origin from springs 

 or the origin from sea- water can equally be advanced as alternatives 

 to the arbitrary assumption of wedges of Trias introduced by 

 paradoxical contortions that are demonstrably absent in many cases 

 with which they deal. 



The thermal springs of the Pyrenees were long since analyzed 

 by Filhol, and their accompanying rocks patiently interpreted by 

 Leymerie. These eminent observers, in 1866, showed me a car- 

 bonaceous metorite whose fall was witnessed, and whose fragments 

 are preserved in the Museum of Toulouse. They furnished me with 

 specimens of its material, and assured me that a portion of its 

 substance bad yielded the formula of humus. Filhol explicitly 

 remarked to me that it apparently carried vestiges of the life of th& 

 original body to which it belonged. I had previously suggested 

 to fellow-students the convenient theory of meteoric origin for every 

 residual difficulty of geology in general. Personally invented theories 

 are thus often crystallized by a fascinatingly confirmatory apparent 

 fact. The practical geologist notes and discards such suggestions 

 in every excursion. Of course, it was practically impossible to 

 ascertain whether the organic matter was originally present or was 

 introduced in the hot meteorite from the soil into which it penetrated 

 deeply when it fell. 



I have found the main problems of the Pyrenees to be con- 

 veniently represented at Dax. The abundant fossils of the Tertiary 

 plain here meet the similarly abundant fossils of the outermost 

 Cretaceous, so that the relative dispositions are defined by independent 

 evidence of everv kind. Desirino- to leave somethingc for later 

 observers, I would nevertheless remark that the problems are even 

 here less easily and rapidly solvable than recent innovators have 

 found them to be at points where none of the means of solution 

 available at Dax have troubled the even course of their decisions. 



Hitherto the entire work of the observers most familiar with the 

 Dax district has shown that the apparently Triassic marls and salt 

 are independent of any special horizon of the Cretaceous fundamental 

 rocks, and it has proved equally impossible to identify them with 

 any special horizon of the Tertiary. It is only certain that they 

 closely accompany the igneous ophites (diabase or dolerite), and that 



