Bryce Canyon, famous for its worldly unique geology, consists of a series of horseshoe-shaped amphitheaters carved from the eastern edge of the Paunsaugunt Plateau. The erosional force of frost-wedging and the dissolving power of rainwater have shaped the colorful limestone rock of the Claron Formation into bizarre shapes, including slot canyons, windows, fins, and spires called "hoodoos".
Long ago, and changing over the great spans of time, the rocky area of of Bryce Canyon was once covered by sea, mountains, desert and coastal plain. Over millions of years, the rock and land was subject to violent storms and severe changes. Earthquakes, mudslides and volcanoes roared upon the primitive earth, forcing, molding and reshaping it. Seas and streams came and went, moving sediment and depositing it in layers.
The Hoodoos of Bryce Canyon are 60 million years old. More changes occurred until sand, gravel and sedimentary deposits filled ancient lakes within the Colorado Plateau. These materials compressed and hardened into sedimentary rock. The hoodoos of Bryce Canyon are 60 million year old sculpted claron rock formations which consist of limestone, dolomite and siltstone layers. The Colorado Plateau has risen over a time period of about sixteen million years.
The Paria River and its streams flowed through the area sculpting and eroding the walls. These sedimentary layers contain lignite, coal and fossils, including evidence of the lush mesozoic period when the climate of the area was tropical with lush plants and a variety of unique animals flourished. The location at the plateau rim allows for hoodoo formation because the steep slope gives the environment needed for the structures to form. At the slope, faults and joints form compressional forces that guide the patterns of erosion.
The yearly weather cycle aids the process needed for a hoodoo to form. In Bryce Canyon it freezes at night approximately 360 days of the year. The freeze and thaw cycle loosens the slope surface, allowing debris to be sluffed off by water run-off. When hiking among the hoodoos at Bryce Canyon, look closely at the fins and hoodoos and you will see the vertical cracks. The material carried away works on the softer rock to create gullies, and ultimately canyons. The hard rock that was left behind is further eroded along its vertical cracks, again subjected to the freeze - thaw cycle carving the hoodoos.
Patterns form through a process of freezing and thawing. The patterns of Bryce's rock formations show off their unique crisscross design formed though this long process of freezing and thawing. The process still continues today, and the rock formations continue to be designed by nature. When water seeps into the fractures of the rocks, it dissolves the calcium carbonate that holds the small rock particles together. In cold weather, the water turns to ice as temperatures drop, then the ice expands pushing the fractures open. The overnight freezing and daytime thaw are abundant, occurring two to three hundred times a year, but since different rocks are of varied hardness, erosion takes place at different rates.
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