The entrance of the glacière was surrounded by woods, which formed a natural rampart to anything like wind. As we stood facing the glacière a great pit opened before us, with a slope about one hundred and thirty-five meters long leading to the bottom. This slope is at first gentle in its gradient, but lower down it steepens to an angle of some thirty degrees so that we were glad to resort to the trail which descends in regular Alpine zigzags. In one place, on the right hand, there were the remains of a stone wall with a door, and local tradition relates that in former times there was a sort of fortified habitation there, which was used in war times as a place of retreat. The lower part of the slope is covered by a protecting roof of rock which, thin at the rim where it is edged with forest, gradually slopes downward overhead so that at the mouth of the glacière we looked back and up what might be described as an immense tunnel. The lower part of the slope was a mixture of broken rocks, mud and ice: the last, however, seemed to be all on the surface, although it was impossible to determine whether it went to any depth.
ICE STALAGMITES, CHAUX-LES-PASSAVANT.
From a Photograph by E. Mauvillier.
At the base of the tunnel we found ourselves on the threshold of an immense, almost circular cave, with a diameter of some fifty meters, rising overhead into a regular vault or dome about twenty-seven meters in height. The entrance to the cave is so large that plenty of daylight is admitted, and the whole cave easily examined. The rocks are of a yellowish brown hue, and I could not help thinking of Nibelheim in Richard Wagner’s Rheingold.
Fig. 1.[2] Vertical Section of Chaux-les-Passavant.