which the harder layers projected knife-sharp in level shelves beyond the soft, crumbling rock. At last these sandstone ruins became plentiful, in the manner of yesterday, and stood grouped about our road in similar chequered yards of light and shade. Again we marvelled at the sureness with which Auda guided our little party through the mazy rocks.
They passed, and we reentered volcanic ground. Little pimply craters stood about, often two or three together, and from them spines of high, broken basalt led down like disordered causeways across the barren ridges; but these craters looked old, not sharp and well-kept like those of Ras Gara, near Wadi Ais, but worn and degraded, sometimes nearly to surface level by a great bay broken into their central hollow. The basalt which ran out from them was a coarse bubbled rock, like Syrian dolerite. The sand-laden winds had ground its exposed surfaces to a pitted smoothness like orange-rind, and the sunlight had faded out its blue to a hopeless grey.
Between craters the basalt was strewn in small tetrahedra, with angles rubbed and rounded, stone tight to stone like tesserae upon a bed of pink-yellow mud. The ways worn across such flats by the constant passage of camels were very evident, since the slouching tread had pushed the blocks to each side of the path, and the thin mud of wet weather had run into these hollows and now inlaid them palely against the blue. Less-used roads for hundreds of yards were like narrow ladders across the stone-fields, for the tread of each foot was filled in with clean yellow mud, and ridges or bars of the blue-grey stone remained between each stepping place. After a stretch of such stone-laying would be a field of jet-black basalt cinders, firm as concrete in tie sunbaked mud, and afterwards a valley of soft, black sand, with more crags of weathered sandstone rising from the blackness, or from waves of the windblown red and yellow grains of their own decay.