Sabino Creek begins 6,000 feet above the desert floor, in the pine forest that shades the slopes of Mt. Lemmon in the Santa Catalina mountains. [Lazeroff, p.11] The Catalinas, like other mountain chains, force moisture from the air as it rises up the mountain slope. Thus, the mountains receive more rain than the surrounding desert. In the summertime, Tucsonans look for billowing cumulus clouds forming over the Catalinas and neighboring Rincon and Santa Rita mountains as an indication of afternoon storms.
Sabino Creek winds its way 10 miles through the mountain canyons before reaching the desert, where much of it eventually sinks into the ground, adding to Tucson's supply of groundwater. [Lazeroff, p.11-12] The amount of water that is found in the creek varies dramatically. In winter, melting snow from the mountaintops combined with the normal winter rainy season leads to a generous amount of water in the creek. It is commonplace for the creek to overflow the stone bridges, leading canyon walkers to hop the rocks edging the bridge or get their feet wet.
By May, much of the water has disappeared, as the long months of relatively dry, hot weather take their toll. At some points the creek disappears entirely, going underground. Still pools dot the creek bed, waiting for the next rain. During the summer monsoons, the creek experiences sudden rushes of water during the torrential downpours. The creek dries out again after the summer storms, waiting for the gentle winter rains to begin the cycle again.
The plants and animals that live near the creek have adapted to the seasonal floods and droughts. Unless there is major flooding, trees and saplings are rarely uprooted, and the grasses quickly spring to life after the floods have passed. Animals have learned to leave the creek bed during heavy rains.
Sabino Canyon is located on the northeastern edge of the Sonoran Desert. [Guide, p.3] This desert experiences 2 annual rainy seasons. About half of the annual rainfall occurs during December, January and February. These are typically long, gentle rains that arrive from the Pacific Ocean. Occasionally, when El Nino is active, these rains can lead to flooding as the ground quickly becomes saturated by the more frequent storms. The summer rain occurs during July, August, and September. Intense, local thunderstorms are produced from moisture driven northwest from the Gulf of Mexico. In Tucson, this is referred to as the "monsoon season," because the winds bring the moisture from the south. In all, 12 inches of rain can be expected in a typical year. This is quite a lot of moisture for a hot, desert climate, and can support a wide variety of plant and animal life.
Temperatures can be extreme in this desert region. Snowfall tends to occur at least once during the winter months, and it has been known to snow as late as April. During the summer months, temperatures climb to well over 105. [Lazaroff, p. 21-22]
The city of Tucson is surrounded by four mountain ranges: the Santa Rita's to the south, Tucson Mountains to the west, Rincon Mountains to the east, and Santa Catalina Mountains to the north. Sabino Canyon is on the southern side of the Santa Catalina's. The Santa Catalina's east-west front range extends some twenty miles from west Tucson to the Redington Pass. [Miller, p. 37] Mount Lemmon is the highest point in the range, rising to just over 9,100 feet. The lowest elevations are from 2,500 to 3,500 feet.
The Santa Catalina Mountains were formed 12 million years ago. They were formed during a period when the western North American continent was being stretched, cracking into blocks, bordered by large, steep faults. [Lazaroff, p.3] The Catalinas were probably only small hills at that time. However, as the continent stretched and blocks around the Catalinas sank forming valleys, the mountain range was left as a high point of land. No sooner were they formed than wind, ice, and water began to erode them. Tucson sits atop thousands of feet of sediments already eroded from the Santa Catalinas and other surrounding mountain ranges.
The rocks of the Catalinas are mostly granite and "Catalina gneiss," a hard metamorphic rock with a layered, or banded appearance. [Lazaroff, p.4] Current theory has it that the gneiss was formed nearly a billion and a half years ago. At that time, a mass of molten rock cooled deep underground, forming a large layer of granite. Another mass of molten rock invaded the deeply buried granite about 45 million years ago. This second rock pooled in the granite in great fingers and sheets. Where they are visible today, these rock layers were stretched before they cooled and hardened, so that they layers are thin. The dark rock layers that we see today are the remains of the ancient granite, the light layers are the younger rock that invaded it 45 million years ago.
The nature of Sabino Canyon's topology and climate lead to an unusual diversity in plant life. Its topology features rugged canyon walls narrowing down to a year-round creek bed. It experiences desert temperatures during the summer, but still can have snow and frost in the coldest part of winter. Finally, two annual rainy seasons contribute more moisture than many other desert regions. View images of Sabino Canyon plant life.
Animal life is abundant, if not always highly visible in Sabino Canyon. Adaptations common to desert wildlife enhances their chance of survival, but does not help canyon visitors in observing animal activity. For example, many birds and other mammals have colors that blend into the landscape, other animals are nocturnal and avoid the extreme heat of the day by foraging for food at night. Some animals that are often found near the entrance to the canyon are the ground squirrel and young white tale deer. View images of Sabino Canyon wildlife.
Search SABIO for more information on Sabino Canyon's climate, animal and plant life, and geology.