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| This view from the Circle Creek Overlook shows the unique weathering characteristics of the granite. The majority of the granite in the park area formed about 2.5 billion years old. These rocks are a part of the Green River Complex, an extensive belt of ancient igneous and metamorphic rocks in the region; these rocks are some of the oldest rocks in the United States. Younger, ligheter-colored granitic plutons locally intruded the ancient rocks about 25 million years ago. Since then, the land has slowly risen and erosion has stripped away rocks at the surface, eventually exposing the granite. |
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