As one leaves the prairie States and nears the great Southwest, he finds Nature in a new mood--she is dreaming of canyons; both cliffs and soil have canyon stamped upon them, so that your eye, if alert, is slowly prepared for the wonders of rock-carving it is to see on the Colorado. The canyon form seems inherent in soil and rock. The channels of the little streams are canyons, vertical sides of adobe soil, as deep as they are broad, rectangle grooves in the ground. Through all this arid region nature is abrupt, angular, and sudden--the plain squarely abutting the cliff, the cliff walling the canon; the dry water-course sunk in the plain like a carpenter's groove into a plank. Cloud and sky look the same as at home, but the earth is a new earth--new geologically, and new in the lines of its landscapes. It seems by the forms she develops that Nature must use tools that she long since discarded in the East. She works as if with the square and the saw and the compass, and uses implements that cut like chisels and moulding-planes. Right lines, well-defined angles, and tablelike tops of buttes and mesas alternate with perfect curves, polished domes, carved needles, and fluted escarpments. In the features of our older landscapes there is little or nothing that suggests architectural forms or engineering devices; in the Far West one sees such forms and devices everywhere. In visiting the Petrified Forests in northern Arizona we stood on the edge of a great rolling plain and looked down upon a wide, deeply eroded stretch of country below us that suggested a vast army encampment, covered as it was with great dome-shaped, tent-like mounds of a light terra-cotta color, with open spaces like streets or avenues between them. There were hundreds or thousands of these earthy tents stretching away for twenty-five miles. Along the horizon was a gigantic stockade of red, rounded pillars, or a solid line of mosque-like temples. How unreal, how spectral it all seemed! Not a sound or sign of life in the whole painted solitude--a deserted camp, or one upon which the silence of death had fallen. Here, in Carboniferous times, grew the gigantic fern-like trees, the Sigillaria and Lepidodendron, whose petrified trunks, for aeons buried beneath the deposit of the Permian seas, and then, during other aeons, slowly uncovered by the gentle action of the eroding rains, we saw scattered on the ground.