The Tepees, a rock formation in Petrified Forest National Park in the U.S. state of Arizona. Named for its large deposits of petrified wood, the park covers about 146 sq mi (380 km2), encompassing semi-desert shrub steppe as well as highly eroded and colorful badlands. The petrified trees that give the park its name date to the Late Triassic, about 225 million years ago.Photo: Finetooth