In the park area the canyon is several miles wide. The canyon rim is about 3,500 feet above sea level and the canyon floor, although highly irregular is approximately 2,700 feet above sea level. The maximum depth of the canyon is about 800 feet. The United States Geological Survey has published an excellent topographical contour map of the canyon, the Fortress Cliff Quadrangle. It can be purchased at the park or from the United States Geological Survey.
The Park area normally receives about 20-30 inches of rainfall per year and has a frost free period of approximately 200-240 days per year. The yearly temperature ranges from 0-70°F in the winter and from 65 to 100°F in the summer. The weather is considered fair about 75% of the time. The nights are cool even in the summer.
ECOLOGY
Palo Duro Canyon is part of the escarpment system that forms the eastern boundary of the Llano Estacado or Staked Plains. The Staked Plains in this area is a nearly-level to gently-rolling terrain covered with a mantle of calcareous loess (a wind-blown silt) that has given rise to deep soils with a clay-loam surface and a clay subsoil. These soils are ideally suited to the growth of short grasses, especially blue grama and buffalo grass. Mesquite, yucca, prickly pear cactus, and forbs are common invaders of overgrazed areas.
Many shallow lake basins (playas) dot the plains with a flora different from the surrounding areas. In the playas, plains grasses are displaced by forbs that are suited to withstand the prolonged flooding within the shallow basins.
Near the canyon, the deep soils can be seen grading into shallow, grayish-brown, gravelly-loam soils. The abundance of grasses decreases and mid grasses such as little bluestem and sideoats grama increase. The mid grasses are better able to absorb nutrients from the less fertile soils near the canyon rim than are the short grasses. Especially conspicuous are increasing numbers of shrubs, particularly the evergreen and scale-leaved junipers. Just along the rim of the canyon, the shrubby mountain mahogany is found.
The rugged terrain of the sides of the canyon, extending from the Ogallala downward through the Trujillo and Tecovas formations to the upper part of the Quartermaster Formation, shows a variety of soil types. On the steeper slopes, plants are unable to gain a foothold as erosion removes soil material as fast as it is formed. On less-steep areas, the well-drained escarpment soil is suited for the development of scarp woodland. The deep, woody roots of trees and shrubs are better able to obtain the deeply infiltrating moisture from these soils than are the shallow and fibrous roots of grasses. The common plants on the level areas are junipers, squaw-bush, and little-leaved sumac. On the drier slopes, feather peabush, catclaw, and salt-bush are found. Groves of oak occur, but not in the abundance found along the escarpment further to the south.
Below the canyon slopes and extending to the creek are a wide variety of soils and a great diversity of plants. Most of the plants of the plains and escarpment are found here. Some of the soils of the nearly level areas are deep, high in fertility, and hold large amounts of water. Tall grasses, such as indiangrass and switchgrass, occur admixed with mid grasses; a rank growth of vine-mesquite grass often occurs in the areas where runoff water collects; and alkali sacaton grass grows on saline soils. Other trees and shrubs include hackberry, soapberry, wafer ash, button bush, foresteria, and Texas buckthorn. Along the creek, cottonwoods, willows, and salt cedar are common.
Because of the varied topography, diversity of plant life, and geographical locations, the canyon affords an ideal habitat for wildlife. Some of the mammals that occur here are the coyote, porcupine, jackrabbit, cottontail rabbit, raccoon, opossum, ringtailed cat, striped skunk, gray fox, white-footed mouse, woodrat, and bat. Mammals that were once common but are now absent or extremely rare are the bison, black bear, black-footed ferret, lobo wolf, cougar, and bobcat. The moose and American elk were introduced into the canyon but are no longer to be found. White-tailed deer, mule deer, and aoudad sheep have also been introduced and are still present. The mule deer is the most common. A great many types of birds are found either as residents of or migrants to the canyon. A few are the golden eagle, red-tailed hawk, sparrow hawk, Mississippi kite, turkey vulture, blue quail, killdeer, nighthawk, roadrunner, red-headed woodpecker, golden-fronted woodpecker, canyon wren, mockingbird, robin, cardinal, meadowlark, Bullock’s oriole, painted bunting, white-crowned sparrow, and lark sparrow.