﻿80 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 18, 



which was probably formed by the wearing away of a substance softer 

 than the other beds. The mass of this rock (about 60 feet wide 

 across the beds) consists of very finely laminated thin-bedded tu- 

 faceous limestone of great hardness, of cream and brown colours, and 

 in great part made up of hard translucent arragonite. The thinnest 

 layers are about two inches and the thickest exceed a foot ; the 

 former are, however, much the most abundant. Some of the courses 

 of darkish grey layers inclose thin coatings of arragonite, and some 

 of the surfaces are mammillary ; particularly where the arragonite 

 has been most elaborated. No one can examine these vertical strata 

 of limestone, tuff, and arragonite, without being convinced that they 

 must have been originally deposited in a more or less horizontal 

 position. If the water which deposited them had cascaded or fil- 

 tered over a bank-side, it never would have formed a succession of 

 perfectly parallel vertical beds, like those now exhibited. In this 

 case, as at St. Alegre and St. Nectaire, in this same region, where 

 great tufaceous deposits are now going on (though of a very different 

 mineral nature from the rock of the Celestins), the tuff thickens out 

 irregularly, according to the downward slope. 



Again, it is impossible (independent of the proofs of fracture and 

 dislocation shown in fig. 1) that these vertically-bedded arragonites 

 could have been so deposited after the present geography of the 

 country was fixed and determined ; for their summits are higher than 

 any ground in the surrounding locality. Nothing, therefore, short 

 of a jet d'eau, like the Geysers, could have thrown up the waters to 

 deposit materials at such an altitude ; whilst no power in nature 

 could arrange falling sediments during their deposit in this vertical 

 position along a front of 250 yards. They extend, in fact, much 

 beyond the point where they are exposed in the sketch (fig. 2), and 

 range under the remains of the old convent, now the farm-house 

 there represented. 



But independent of such reasoning, I obtained a distinct proof of 

 the comparatively high antiquity of this dislocation, by observing 

 that the rugged and jagged tops of these hard beds, resembling in 

 miniature the peaks and needles of some crystalline mountains, are 

 covered over by coarse gravel, in which granite, porphyry, schist, 

 and other rocks occur, including some fragments of the arragonite 

 itself (see a section of the gravel at b\ fig. 2). As this detritus, 

 rising to the height of 50 to 60 feet above the Allier, could never 

 have been placed there in the recent period (where no streams flow), 

 so it is evident that the dislocation, by which the strata of the Ce- 

 lestins were broken off from the contiguous horizontal masses and 

 thrown into their vertical positions, took place at a very remote period. 

 Since that dislocation occurred the tops of the beds have been deeply 

 corrugated, and thus left with outlines wholly dissimilar from those 

 of any strata deposited by a modern spring. The original move- 

 ments which threw these masses of stone upon their edges in a di- 



large isolated flagstones resembling tombstones. The chief mass of the vertical 

 strata is exposed in part in the rocks marked a, and is thence continued under the 

 building, or towards Vichy and its line of springs. The spring of the Celestins is 

 on the left. 



