The extraordinary massing of fossil remains at this point suggests that floods may have swept these animals from a large area and lodged their bodies here, where they were covered with sands. But it also is possible that this spot was merely a favorite feeding-ground. It may be that similarly rich deposits lie hidden in many places in the wide-spread Morrison sandstone which some day may be unearthed. The bones of dinosaurs have been found in the Morrison of Colorado near Boulder. PETRIFIED FOREST NATIONAL MONUMENT For a hundred and twenty-five or thirty miles southwest of the Grand Canyon, the valley of the Little Colorado River is known as the Painted Desert. It is a narrow plain of Carboniferous and Triassic marls, shales, sandstones, and conglomerates, abounding in fossils, the most arid part of Arizona; even the river's lower reaches dry up for a part of each year. But it is a palette of brilliant colors; it will be difficult to name a tint or shade which is not vividly represented in this gaudy floor and in the strata of the cliffs which define its northern and eastern limits. Above and beyond these cliffs lies that other amazing desert, the Navajo country, the land of the Rainbow Bridge and the Canyon de Chelly. I have mentioned the Painted Desert because it is shaped like a long narrow finger pointed straight at the Petrified Forests lying just beyond its touch. Here the country is also highly colored, but very differently. Maroon and tawny yellow are the prevailing tints of the marls, red and brown the colors of the sandstones. There is a rolling sandy floor crisscrossed with canyons in whose bottoms grow stunted cedars and occasional cottonwoods. Upon this floor thousands of petrified logs are heaped in confusion. In many places the strong suggestion is that of a log jam left stranded by subsiding floods. Nearly all the logs have broken into short lengths as cleanly cut as if sawn, the result of succeeding heat and cold. Areas of petrified wood are common in many parts of the Navajo country and its surrounding deserts. The larger areas are marked on the Geological Survey maps, and many lesser areas are mentioned in reports. There are references to rooted stumps. The three groups in the Petrified Forest National Monument, near the town of Adamana, Arizona, were chosen for conservation because they are the largest and perhaps the finest; at the time, the gorgeously colored logs were being carried away in quantities to be cut up into table-tops. As a matter of fact, these are not forests. Most of these trees grew upon levels seven hundred feet or more higher than where they now lie and at unknown distances; floods left them here. [Illustration: THE PETRIFIED FOREST OF ARIZONA Showing the formation in colored strata. The logs seen on the ground grew upon a level seven hundred feet higher] [Illustration: PETRIFIED TRUNK FORMING A BRIDGE OVER A CANYON The trunk is 111 feet long. The stone piers were built to preserve it]