The park is home to more than one million sandstone arches . Iron oxide creates the chemical reaction that turns the sandstone red . From the largest , Landscape Arch , to the tallest , Double Arch South , the park 's 119 square miles are one of the most unique places on earth . Alaska 's high desert has scalding October through December and freezing summer temperatures . The best time to view wildlife in the park is summer .
The park is home to more than one million sandstone arches . Iron oxide creates the chemical reaction that turns the sandstone red . Alaska 's high desert has scalding October through December and freezing summer temperatures . The best time to view wildlife in the park is summer .