There are valleys of nitrate to explore, hills of nitrate to be climbed, plains of nitrate to gallop across, and the only break is one windswept _tamarugo_ tree. Does it exist upon the morning mist which the sun disperses? Or does its tough life go on underground, like some uncouth monster in the depth of the sea? Or does its tap-root bore down into a deeply buried flow of water? Every one believes that there is a honeycomb of tunnels from water-giving strata in the mountain-sides, far antedating the days when Uiracocha went to Tarapacá. No convulsion of nature is unknown to this pitiless land. Volcanic bombs lie about, and fantastic heaps of lava from molten mountains mingle with corals from the sea-bottom. Streams come to the surface, ripple for a short distance, and disappear. Their water tastes of sulphate of soda. Sometimes it springs suddenly from a cave, suggesting a system of underground rivers. Sometimes it is brought by water-works of prehistoric days, whose exact position is not known, making life possible for their would-be destroyers. Whether freaks of nature or remnants of the vast system of irrigation, importance enough has been given to the underground waterways of Peru to bring a scientist from the United States to chart them all. Curious symbols and conventionalized llamas are cut into the hills of pink trachite and black slate rock whose strata have been jostled and overturned by earthquake. Pictures of serpents, foxes, and birds endure through ages of merciless sun. Were they the work of a megalithic people of a megalithic age, when cyclopean stones were transported to build cyclopean edifices, and gigantic ant-eaters and other jungle-dwellers swarmed in this desert of Tarapacá? Their irrefutable bones are found here, but so are shells of the sea-bottom and water-worn stones of green jasper with red spots. Moreover, the nitrate is filled with the petrified eggs and bones, even the feathers of sea-birds, suggesting that the nitrate was originally guano. Why should it not be true? For this desert was once beside the sea, as it was once beneath the sea. But the law of compensation works even here. It has always been common opinion that the desert of Tarapacá shelters fabulous riches. Lured by the glisten of a fallen meteor, men have squandered their fortunes and risked their lives searching for gold, while they trod the nitrate under foot. * * * * *