272 



KNOWLEDGE 



[December 1, 1900. 



tracks, these valued relics ai'e eagerly seized ou by the 

 peasantry. It must be a source of much amioyance to 

 know that the great suow-field of Mont-de-Lans covers 

 similar stratified rocks, which have been raised too high 

 even for tire industry of a Frenchman. 



The road that we have selected climbs onward to 

 La Grave in a valley of impressive barrenness. The 

 gorge of Gondo on the Simplon Pass possesses many 

 similar features ; but here the continuous rock, the 

 jutting spurs without a sign of vegetation, the huge 

 fallen rocks, unsoftened by moss and even unflecked by 

 lichens, force on us a growing sense of desolation. 

 Nothing now remains, as we leave the hamlet of Le 

 Dauphin, but schist and granite, the mica gleajiiing on 

 the fractured sur-faces, the white veins, cold and dead, 

 making streaks upon the great rock-walls. High up on 

 the right, three or four little tongues of ice creep over 

 from the unseen plateau; in front of us, a huge bare 

 crag glows crimson, answering the sun that already has 

 set beyond Grenoble. Then the darkness grows ; the 

 cliffs become black, save for the foaming bands of half- 

 seen water-slides and falls; we push through lengthy 

 tunnels, and both hear and feel the moisture dripping 

 through the clefts ; then we emerge again, as from a 

 tomb, into a world where nothing seems alive. 



Suddenly this world changes; the edges of the ice 

 above us become, as it were, translucent, tinged with a 

 green light from behind; ou our left, the upper half 

 of the precipices stands out, evei-y crag and scar 

 revealed ; while across our path, and ou the nearer 

 taluses, the blackness seems to deepen, for we are still 

 far down in the ravine, lost in the shadow of the 

 Pelvoux. But the moon is rising, full and clear across 

 the snows; already the light^shafts cross the valley, 

 bor-ne upon the tiny globules of the mist, which is too 

 thin to be otherwise apparent; the triangular dark 

 spaces left between these luminous bars are the air- 

 shadows of the unseen crests. 



Mile by mile, we near the close of the ravine, where 

 a series of overfolded and repeated Mesozoic strata forms 

 a grass-clad region, leading away to the Col du Lautaret, 

 2075 metres (6806 feet) above the sea. Near the hospit> 

 able village of La Grave, § the peaks of the granite mass 

 come into view upon the right; the moon seems poised 

 for a moment on the very summit of the Meije, her disc 

 intensely brilliant in the blue-black of an Alpine sky. 

 The great snow-basins, and the glaciers oozing from 

 them, form mysterious white masses, clinging to the 

 highest slopes. The long Combe de Malaval is over, 

 and the heart of Dauphine is gained. 



Next morning, in the cloudless sunlight, we can 

 appreciate the contrast between the Jurassic strata of 

 this pastoral upland and the granite mass of the high 

 Alps. The former consist largely of dai-k and shining 

 shales, with intercalated bauds of limestone; where thev 

 are squeezed up almost to the snow-line, they appear 

 coal-black under the white fields and the translucent 

 masses of tlie ice. The storms of rain, intense at these 

 high altitudes, have cai'ved gullies in them, irrespective 

 of their bidding, much like the channels cut in soft clay 

 at ordinary levels. Above them, the granite forms a 

 number ol peaks, w'hich long defied the climbers, with 

 flanking riii/iii'ne>:, such as one sees on the Diasxif of 

 Mont Blanc. 



While the Mont Blanc range is an elongated mass of 

 granite, penetrating the schists, absorbing and including 

 them, and exposed over a distance of 40 kilometres, the 



§ Vorv dillerent from the La GraTe doscribecl by explorers thirty 

 years ago. 



Pelvoux mass is an almost circular knot, 15 to 20 

 kilometres across, and perhaps only the crest of a far 

 larger subterranean dome. In both cases, the granite 

 has been brought to light by the movements that cul- 

 minated in Miocene times, while Jurassic strata have 

 been caught up on the flanks in the form of deep or 

 recumbent synclinals, formed dimng the crumpling of 

 the rocks that lay below. || 



The ascent to the Col du Lautaret from La Grave 

 thus shows us, far below upon cm- right, a valley worn 

 in the softer rocks, extending far into the massif, and 

 then closed abruptly against the broad Glacier of Arsine. 

 A stream, the upper jjart of the Romanche, has laid hold 

 of this weak band of overfolded strata, and has produced 

 a valley 3000 feet in depth. The products of erosion 

 are thrown out in a pretty delta against the meadows 

 of Villar d'Arene. The granite on the east side of this 

 Mesozoic infold is forced up by the earth-pressures until 

 it overlies the Trias, which in turn rests on Liassic 

 limestone ; we now know that such inversions of the 

 natural order are a frequent feature of mountain-chains. 

 This deep synclinal between two gi'anite masses, forming 

 the upper valley of the Romanche, has its counterpai-t 

 in the glorious Allee Blanche luider the Italian aiguilles 

 of Mont Blanc. 



To the east of the Col du Lautaret, the characters of 

 the Alpine foot-hills reappear. The brown limestone 

 crag of the Grand Galibier reminds us of Tyrol ; the 

 mountains about the foi-tress of Briaujon, to which we 

 now descend, have their counteiiDarts in the southern 

 Juras. A band of Coal-Measures comes up in their 

 midst, much broken and displaced ; it is the same as 

 that which contains beds of gi'ajjhite on the Little St. 

 Bernard, and which can be traced north-eastward right 

 into the valley of the Rhone. 



We now join the Durance, one of the most vehement 

 of Alpine streams. The whole region bears witness 

 to disastrous denudation. A few wet days in August 

 of the present year converted it in places into a mere 

 wilderness of stones. Already, as we come down from 

 the Lautaret, we find one of the long tunnels broken 

 into by a stream, and choked with debris from the moun- 

 tains. A little further on, when we have traversed the 

 rough track constructed on the outside of the tunnel, 

 we find huge blocks deposited ou the crown of a bridge, 

 which lia.s naturally given way beneath them. The 

 former stream-hollow has, however, become filled by a 

 land-slide, and is thus not difficult to cross. Down below 

 Brian^on, similar havoc has been wrought on the surface 

 of the broad dctrital cones, which everywhere mark the 

 entry of the lateral streams on the main valley of the 

 Durance. The villages, like those of Karinthia, are 

 commonly built on the summit of these cones, which 

 spread out, in huge shifting fans, on either side of their 

 main axes. Wooden groins, like those set to control the 

 movements of sea-beaches, are constructed in the more 

 dangerous portions of the cones ; here and there, the 

 movement of the surface has broken them across, while 

 the pebbles have poured through and over them like 

 a flood. The country is one in which denudation can 

 be felt; the very fields of the peasantry way disappear 

 into the Durance, or may be buried in an hour beneath 

 an oozing stream of stones. 



The older alluvium of the valley, in which ravines 

 have been carved by the modern action of the streams, 

 still projects in patches from the mountain-walls ; many 

 of these masses of mud and gravel are the relics of 

 ancient and majestic land-slides. The road has to be 



II Termier, op cif., p. 20. 



