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.

You first see Nature beginning to form the canon habit in Colorado and making preliminary studies for her masterpiece, the Grand Canon.  Huge square towers and truncated cones and needles and spires break the horizon-lines.  Here all her water-courses, wet or dry, are deep grooves in the soil, with striking and pretty carvings and modelings adorning their vertical sides.  In the railway cuts you see the same effects—­miniature domes and turrets and other canon features carved out by the rains.  The soil is massive and does not crumble like ours and seek the angle of repose; it gives way in masses like a brick wall.  It is architectural soil, it seeks approximately the right angle—­the level plain or the vertical wall.  It erodes easily under running water, but it does not slide; sand and clay are in such proportions as to make a brittle but not a friable soil.

Before you are out of Colorado, you begin to see these novel architectural features on the horizon-line—­the canon turned bottom side up, as it were.  In New Mexico, the canon habit of the erosion forces is still more pronounced.  The mountain-lines are often as architectural in the distance, or arbitrary, as the sky-line of a city.  You may see what you half persuade yourself is a huge brick building notching the horizon,—­an asylum, a seminary, a hotel,—­but it is only a fragment of red sandstone, carved out by wind and rain.

Presently the high colors of the rocks appear—­high cliffs with terra-cotta facades, and a new look in the texture of the rocks, a soft, beaming, less frowning expression, and colored as if by the Western sunsets.  We are looking upon much younger rocks geologically than we see at home, and they have the tints and texture of youth.  The landscape and the mountains look young, because they look unfinished, like a house half up.  The workmen have but just knocked off work to go to dinner; their great trenches, their freshly opened quarries, their huge dumps, their foundations, their cyclopean masonry, their half-finished structures breaking the horizon-lines, their square gashes through the mountains,—­all impress the eyes of a traveler from the eastern part of the continent, where the earth-building and earth-carving forces finished their work ages ago.