It was light now and the sun shone fairly on Ab's place of refuge. As his senses brought to him full appreciation he wondered at the scene about him. He was in a glade so depressed as to be a valley. About it, to the east and north and west, in a wavering, tossing wall, rose the uplifting line of fire through which he had leaped, though there were spaces where the height was insignificant. On the south, and extending till it circled a trifle to east, rose a wall of rock, evidently the end of a forest-covered promontory, for trees grew thickly to its very edge and their green branches overhung its sheer descent. Coming from some crevice of the rocks on the east, and tumbling downward through the valley, was a riotous brook, which disappeared through some opening at the west. Within this area, thus hemmed in by fire and rock, appeared no living thing save the birds which sang upon the bushes beside the small stream's banks and the butterflies which hung above the flowers and all the insect world which joined in the soft, humming chorus of the morning. It was something that Ab looked upon with delighted wonder, but without understanding. What he saw was not a marvel. It was but the result of one of many upheavals at a time when the earth's cooled shell was somewhat thinner than now and when earthquakes, though there were no cities to overthrow, at least made havoc sometimes by changing the face of nature. There had come a great semi-circular crack in the earth, near and extending to the line of the sheer rock range. The natural gas, the product of the vegetation of thousands of centuries before, had found a chance to escape and had poured forth into the outer world. Something, perhaps a lightning stroke and a flaming tree, perhaps some cave man making fire and consumed on the instant when he succeeded, had ignited the sheet of rising gas, and the result was the wall of flame. It was all natural and commonplace, for the time. There were other upleaping flame sheets in the surrounding region forever burning--as there are in northern Asia to-day--but Ab knew of these fires only from Old Mok's tales. He stood wonderstruck at what he saw about him.