Canyonlands is part of a group of parks located in southeast Utah that includes Arches National Park, as well as Hovenweep and Natural Bridges National Monuments. In addition to sharing a headquarters facility and administration, research in these parks is coordinated by a group resource management division, and projects described here include activities throughout the area.
Canyonlands National Park lies near the middle of the Colorado Plateau, a geologic region some consider to be a northern extension of the high-pressure Sonoran desert. Others consider the Plateau to be an eastern extension of The Great Basin, a desert in the rain shadow of the Sierra Nevada Mountains. High pressure deserts generally form at the middle latitudes (30 degrees) in each hemisphere where warm, dry air masses descend toward the earth's surface. Rain shadow deserts form in localized high pressure zones caused by warm, dry air descending from mountain ranges. The Colorado Plateau is also in the interior of a large continent, far away from significant water sources. Each of these factors may contribute to the arid climate of the Colorado Plateau.
Because of the elevations throughout the region, with a mean of around 3,000 feet and peaks over 12,000 feet above sea level, the Colorado Plateau is also known as a cold or high desert. Though low relative humidity allows greater penetration of solar radiation, winter air temperatures frequently drop below freezing. In turn, summertime air and especially ground temperatures can reach levels lethal for many organisms. After sunset, the ground rapidly loses heat to the night sky and ambient air temperatures may drop significantly before dawn. Temperature fluctuations of over 40 degrees in a 24-hour period are not uncommon. As a result of these extreme conditions, the plant and animal communities found here have evolved unique adaptations, and many species are endemic to the region.
Canyonlands receives an average of 9.2 inches of precipitation a year, more than many deserts. However, the potential evapotranspiration approaches 85 inches annually, which leaves a water deficit of around 76 inches. August is generally the wettest month, as weather systems from the southwest bring brief, intense tropical storms. Seasonal changes in the Jet Stream bring precipitation from the northwest at the beginning and end of winter (October and April, respectively). Despite these patterns, precipitation is highly variable both temporally and spatially, further complicating the lives of desert organisms. Annually, or even during a single storm, a given patch of desert may receive significantly more or less water than a neighboring patch less than a mile away.
The Canyonlands ecosystem is described as a high desert, characterized by hot summers, cold winters, less than ten inches of rain each year, and low relative humidity. Formed out of the vast sedimentary rock deposits of the Colorado Plateau, the Canyonlands area has been eroded into a network of canyons, mesas and deep river gorges that provides a variety of habitats for animals. From the heavily vegetated riparian areas found in some canyon bottoms, to occasional grasslands bordered by large expanses of slickrock, plant and animal species have developed many communities and use a variety of techniques to endure the extremes of the desert environment.
Two unusual communities are common in the Canyonlands area and intrigue both scientists and visitors: cryptobiotic soil and potholes. Cryptobiotic soil is a living groundcover that forms the foundation of high desert plant life. Potholes are naturally occurring basins in sandstone that collect rainwater and wind-blown sediment. These potholes harbor organisms that are able to survive long periods of dehydration, and also serve as a breeding ground for many high desert amphibians and insects. Both of these communities are very vulnerable to human impacts.
Geologic processes have played the most important part in shaping the desert ecosystem of Canyonlands. The arid climate and sparse vegetation allow the exposure of large expanses of bare rock, while the deep canyons of the Colorado and Green Rivers reveal 300 million years of geologic history.
The Evolution of Canyons
Canyonlands is located within a geologic region called the Colorado Plateau. For millions of years, water and wind deposited materials from a variety of environments onto what is now the Colorado Plateau. The area was repeatedly flooded and then dried by intense sun and wind, and the remains of these ancient seas and deserts were slowly compressed into layers of sedimentary rock. Massive geologic uplifts to the east and north brought torrents of mountain rain and snowmelt, carving the deeply incised river channels of the Green and Colorado rivers. Water from nearby mountain ranges like the Abajos, La Sals, and Henrys drains into these rivers, eroding the landscape further into a network of tributary canyons.
Most of the rock stata around Canyonlands are flat. However, massive folds and faults in the land resulted from a thick layer of salt that shifted under the weight of the overlying sandstone. In many places, this movement caused the surface rock to fracture or collapse downward, forming "synclines" and "anticlines." Over time, flash floods and the action of water freezing and thawing enlarged these fractures and eroded the sandstone features into the landscape seen today.
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