Then we come to more mountain ranges running right across the desert's face, their bare rocks shivered and shelving down into broken fragments at their feet; then sharp-edged, jagged hills--not rounded, plump, and well-fed hills, such as we have at home. They are the bones of the hungry landscape showing through. Then we come to bare table-lands and the empty beds of rivers and lakes that long ago went dry; valleys scattered with boulders of all sizes and in every imaginable position; and so on over into the Arabian desert, with its flats of white sand closed in by high cliffs, and vast stretches of black and red gravel. More of the sand and gravel of the desert is red than yellow; but some of it is white and some of it is black. [Illustration: AN OASIS] [Illustration: THE DARK HILLS AND THE FIGURES IN WHITE "The Baths of the Damned," the superstitious Arabs call the region of the Northern Sahara in which you come upon these strange white figures. The fearsome name was suggested by the fact that the figures slowly rise from some hot region inside the earth. In reality they are mounds of carbonate of lime deposited by the water of hot springs heavily charged with dissolved limestone. Similar springs in our Yellowstone Park spout up in the form of geysers and form "geyser basins"--huge stone tubs. Here in the desert the water doesn't spout; it bubbles up slowly and so builds the mounds. In the background you see black masses of volcanic rock, for this, like Yellowstone Park, is a volcanic region where the underground rocks haven't cooled off. ] A CHAOS OF COLOR IN THE ROCKS The desert wears rocks and stones of as many colors as the jewels of Oriental kings. It also runs much to solemn black in its heaps of volcanic rock with cold limestones on the heights; but you can see blue-grays, browns, ochres of every shade gleaming in the sun, the reds of the rusting iron in them staining the precipices and the walls; and there are purples and pinks and dark greens and violets. These colored rocks are often fantastically mixed together, like the colors on an Easter egg. THE SKELETONS OF THE DEAD RIVERS And here we come upon one of those skeletons of dead rivers that I spoke about. There they are, the river valleys and the river beds, full of sand and gravel, and with boulders along the banks, and branch valleys running into them; a river system all complete but for one thing--water. It's just as if the main valley and the branches had been made all ready but the river never came; or as if there had been rivers there once but they couldn't stand the climate! Of course, when a cloudburst comes along it helps itself to these ready-made river-beds; but for the most part they stand as empty as the ruins on the desert's edge in which ... the lion and the lizard keep The courts where Jamshyd gloried and drank deep.[30] [Footnote 30: "The Rubaiyat" of Omar Khayyam.]