The San Rafael Swell is a large geologic feature located in south-central Utah about 16 miles (26 km) west of Green River, Utah. The San Rafael Swell, measuring approximately 75 by 40 miles, consists of a giant dome-shaped anticline of sandstone, shale, and limestone that was pushed up during the Paleocene Laramide Orogeny 60–40 million years ago. Since that time, infrequent but powerful flash floods have eroded the sedimentary rocks into numerous valleys, canyons, gorges, mesas, buttes and badlands.
Zuni is one of the few points along the south rim of the Grand Canyon that has no road, trail or signpost, though it is easy enough to reach, by walking through the open pine forest for half a mile, staying close to the canyon edge. Grand Canyon National Park, in Arizona, is home to much of the immense Grand Canyon, with its layered bands of red rock revealing millions of years of geological history. In Grand Canyon National Park, lightning strikes an average of 25,000 times per year.
