February 28, 1895J 



NATURE 



4u 



To give any account of even the caverns of the 

 Causses, which occupy the larger part of the book, 

 would occupy too much space ; so we content ourselves 

 with a brief sketch of one of the most remarkable — that 

 of Padirac, in the Causse de Grammat ; and, after all, 

 caves generally exhibit a strong family likeness. On a 

 rocky plain a gulf, nearly forty yards across, opens out 

 suddenly, as shown in Fig. 2, for which and the one on 

 p. 410, we are indebted to the courtesy of the pub- 

 lishers. The greatest depth is just over twice the 

 breadth, but a huge pile of debris rises from the bottom 

 up to nearly fifty-nine yards from the surface. This leads 

 cm either side to a gallery. One of these ascends gently 

 upwards, for about a couple of hundred yards, to a spot 

 where a stream bursts from the rock. The other gallery, 



Alps, being most frequent in the more eastern region, 

 where sometimes a bare rocky tract is almost riddled by 

 swallow-holes {dolinas) great or small. From the Karst 

 district they may be followed through the Alps of 

 Dalmatia into the limestone region of Greece ; they exist 

 also in the carboniferous limestone of England, Belgium, 

 and America. One might almost say ubi calx, ibi 

 spelunca. 



M. Martel notices, but appears to have paid less 

 attention to, the curious caves called glacieres, so 

 pleasantly described by Canon Browne in his " Ice Caves 

 of France and Switzerland." In these the walls are 

 hung with sheets and festoons of ice, and thick masses 

 of it cover the floors. In summer-time the temperature 

 inside them keeps very near to the freezing-point. M. 



Vtr., 2.— Sh.llt Icl.l 



t^ Ilie five ot l-'.idir.ic. 



which is also traversed by this stream, extends for about 

 a mile and three-quarters, following a rather serpentine 

 course, which, in one part, bends at right angles to 

 its former direction. At last it ends in a lake and 

 a cul de sac. The cave is generally rather narrow, 

 not many feet in width, but here and there broadens 

 out into a large hall ; the roof, also, rises and falls, 

 its height not unfrequently being from forty to sixty 

 feet — occasionally a good deal more. Padirac contains 

 stalacites, stalagmites, and basin-shaped deposits of 

 calcic carbonate ; in short, is a thoroughly typical cave, 

 with the not infrequent addition of a huge swallow-hole. 

 Dozens of similar caverns may be found in this curious 

 limestone region. They are abundant, under various 

 names, in the Jura and in the limestone districts of the 

 NO. 1322, VOL. 51] 



Martel suggests that in winter they become filled with 

 coldair, which remains there like the carbonic anhydride 

 in ?igrotto del cane. But such as we have seen, appear to 

 be better explained as natural ice-houses, where the 

 summer warmth is insufficient to dispose of the snow 

 and ice which had accumulated in the winter. 



Is it possible that occasionally these swallow-holes and 

 caves may be memorials of an age when the climate was 

 colder than it is at present ? Both are sometimes dry. 

 In the case of the cave, this may be explained by the 

 water having worked out a new, and as yet undiscovered, 

 path ; but some swallow-holes open out, like the mouths 

 of wells, on gentle slopes or rocky plains, apparently 

 disconnected from any system of drainage. They seem 

 too large to be explained — like those countless pipes in 



