Geology
Walnut Canyon lies on the Colorado Plateau and cuts through the Permian Kaibab Limestone, which exposes the Toroweap Formation and Coconino Sandstone. The Kaibab formation also forms the rim of the Grand Canyon. Crossbedding is present in the Coconino Sandstone.
The Walnut Canyon site contains Walnut Creek, which carved a 600 foot deep canyon that flows east. The creek joins into the Little Colorado River en route to the Grand Canyon. The creek has also created a varied and abundant array of vegetation. The shaded, north- facing walls are covered in fir and ponderosa pine trees. The sunny, south facing slopes have agaves and several species of cactus including opuntia, echnocereus and cholla. The floor of the canyon is home to several species of walnut trees, for which the canyon is named.
The rocks in the canyon walls are formed of three distinct layers - the upper third of Walnut Canyon's walls contain Kaibab limestone that varies in layers and hardness, where the cliff dwellings are found, which overlies steep, scrub covered slopes of the Toroweap Formation, while the lowest third is the sheer-walled, cross-bedded Coconino Sandstone. Many layers of the limestone eroded, creating alcoves that the Sinagua Indians used as cave-dwellings.
Today a variety of archeological and natural resources are preserved on approximately 3600 acres.
Read more about this topic: Walnut Canyon National Monument