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.

Other Formations:
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" (see glossary). 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.

Cliff Profile
Many cliffs in the Canyonlands basin show classic profiles which can be seen throughout the southwest. The layers were formed out of a variety of materials during different periods of geologic time. When and how the layers were deposited has great bearing on how they look today. The layers are listed here in descending order (going back in time). See: Cliff Profile

Desert Varnish
Desert varnish is the thin red to black coating found on exposed rock surfaces in arid regions. Varnish is composed of clay minerals, oxides and hydroxides of manganese and/or iron, as well as other particles such as sand grains and trace elements. The distinctive elements are Manganese (Mn) and Iron (Fe). See: Desert Varnish

The Needles:
About ten million years ago, the Colorado Plateau was pushed up thousands of feet and rivers, such as the Colorado and the Green, cut down and carved deep canyons. Water, the primary force of erosion, eats away or weathers rock by attacking the cement holding the sand grains together. Moreover, during storms, rushing water knocks loose sand and rocks as it flows down washes causing additional erosion. The water naturally acts faster on areas of weakness within the rock, such as fractures and cracks. The Needles occur in an area with many fractures called joints.
See: Needles

Upheaval Dome:
Canyonlands is a place of relative geologic order. Layers of sedimentary deposits systematically record chapters in the park's past. With some exceptions, these layers have not been altered, tilted or folded significantly in the millions of years since they were laid down by ancient seas rivers or winds.
See: Upheaval Dome