Jack Dykinga / Hoodoo with rock cap on textured Dakota stone and softer Entrada sandstone, sunset, Glen Canyon National Recreation Area, Arizona, USA

Lynn M. Stone / American bison (Bison bison), rolling in new dust wallow, Wind Cave National Park, South Dakota, USA. Non-ex.

Lynn M. Stone / American Bison (Bison bison) using horns and head to loosen up mound of Prairie Dog burrow to use as dust wallow. Note Prairie Dog in burrow lower right, Wind Cave National Park, South Dakota, USA, J...

Lynn M. Stone / American bison (Bison bison) bull on short-grass prairie, near badlands characteristic of the park, Theodore Roosevelt National Park, North Dakota, USA. June.

LYNN M. STONE / Bison herd {Bison bison} grazing on plains, South Dakota, USA

LYNN M. STONE / Mustang herd (American wild horse) {Equus caballus} Badlands, North Dakota, USA

LYNN M. STONE / American wild horses Mustangs {Equus caballus} on South Dakota Plains, USA, 1999

LYNN M. STONE / Mustangs crossing prairie {Equus caballus} Badlands NP, North Dakota, USA

LYNN M. STONE / Herd of American wild horses / mustangs {Equus caballus} Badlands, North Dakota, USA

LYNN M. STONE / Bison grazing on plains {Bison bison} Badlands NP, North Dakota, USA

LYNN M. STONE / Mustang / Wild horse, mare and foal {Equus caballus} Badlands NP, North Dakota, USA

LYNN M. STONE / Mustang / Wild horse, herd grazing {Equus caballus} Badlands NP, North Dakota, USA

LYNN M. STONE / Cliff swallow nest colony on cliff {Petrochelidon pyrrhonota} South Dakota, USA

LYNN M. STONE / American wild horses / Mustangs {Equus caballus} on North Dakota Badlands USA 1999