Jeff Foott / Skyline Arch, Arches National Park, Utah

Jeff Foott / Delicate Arch and the La Sal Mountains, Arches National Park, Utah

Jeff Foott / Winding road and sandstone formations, La Sal Mountains, Arches National Park, Utah

Jeff Foott / Sandstone rock formations, La Sal Mountains, Arches National Park, Utah

Tim Fitzharris / Rock arch, Atuh Beach, Nusa Penida, Bali, Indonesia

Jeff Foott / Fremont Cottonwood (Populus fremontii) trees in autumn, Bentonite Hills, Capitol Reef National Park, Utah

Jeff Foott / Sandstone rock formations, Theodore Roosevelt National Park, North Dakota

Daniel J. Cox / Gray Wolf (Canis lupus) pack on ridge in winter, Lamar Valley, Yellowstone National Park, Wyoming

Chien Lee / Limestone rock formations, Snow Mountains, Papua, Indonesia

Benjamin Olson / Rock formations and mountain range, Cordillera Paine, Torres del Paine National Park, Chile

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on ridge, Alcedo Volcano, Isabela Island, Galapagos Islands, Ecuador

Tim Fitzharris / Church Rock, volcanic neck formation with view into Monument Valley, Arizona