In this enclosure is a natural pit, of which the north side is a sheer rock, of the ordinary limestone of the Jura, with a chasm almost from the top; while the south side is less steep, and affords the means of scrambling down to the bottom, where a cave is found at the foot of the chasm, passing under the road.  The floor of this small but comparatively lofty cave is 52 feet below the surface of the earth, and slopes away rapidly to the west, where, by the help of candles, the rock which forms the wall is seen to stop short of the floor, leaving an entrance 2 or 3 feet high to an inner cave—­the glaciere.  The roof of this inner cave rises slightly, and its floor falls, so that there is a height of about 6 feet inside, excepting where a large open fissure in the roof passes high up towards the world above.  At one end, neither the roof nor the floor slopes much, and in this part of the cave the height is less than 3 feet.

It would be very imprudent to go straight into an ice-cave after a long walk on a hot summer’s day, so we prepared to dine under the shade of the trees at the edge of the pit, and I went down into the cave for a few moments to get a piece of ice for our wine.  My first impression was that the glaciere was entirely destroyed, for the outer cave was a mere chaos of rock and stones; but, on further investigation, it turned out that the ruin had not reached the inner cave.  In our previous visit we had noticed a natural basin of some size and depth among the trees on the north side of the road, and we now found that the chaos was the result of a recent falling-in of this basin; so that from the bottom of the first cave, standing as it were under the road, we could see daylight through the newly-formed hole.

The total length of the floor of the inner cave, which lies north-east and south-west, is 51 feet; and of this floor a length of about 37 feet was more or less covered with ice, the greatest breadth of the ice being within an inch or two of 11 feet.  Excepting in the part of the cave already mentioned as being less than 3 feet high, we found the floor not nearly so dry, nor so completely covered with ice, as when we first saw the glaciere, three years before, in the middle of an exceptionally hot August.  Under the low roof all was very dry, though even there the ice had not an average thickness of more than 8 inches.  It may be as well to say, once for all, that the ice in these caves is never found in a sheet on a pool of water; it is always solid, forming the floor of the cave, filling up the interstices of the loose stones, and rising above them, in this case with a surface perfectly level.

[Illustration:  Ice-columns in the glaciere of la Genolliere.]