Matthew Maran / Hikers resting under an overhanging cliff on the West Coast Trail. Pacific Rim National Park, Vancouver Island, Canada, September 2010.

Juergen Freund / Carver Huimes Namusu carves out a groove from the rim of a coconut wood bowl to make space for the nautilus mother of pearl inlay, Chea Village, Marovo Lagoon, Solomon Islands, Melanesia, Pacific, Jul...

Markus Varesvuo / Robin (Erithacus rubecula) perched on rim, Spain, December

LYNN M. STONE / Portrait of Golden Retriever puppy with paw on rim of basket full of gourds, Connecticut, USA

Tim Fitzharris / Boulder in desert, North Rim, Grand Canyon National Park, Arizona

Yva Momatiuk & John Eastcott / Mustang (Equus caballus) group on canyon rim in summer with thunder clouds forming overhead, Montana

Gerry Ellis / Lesser Flamingo (Phoenicopterus minor) flock on rim of Lake Bogoria, Lake Bogoria National Reserve, Kenya

Donald M. Jones / California Condor (Gymnogyps californianus), tagged with radio transmitter, South Rim of Grand Canyon, Arizona

Nick Garbutt / Ruwenzori Side-striped / Coarse Chameleon (Chamaeleo rudis) from the montane forests on the rim of the Ngorongoro Crater (1800-2000m asl), Conservation Area, Tanzania. February.

Nick Garbutt / Ruwenzori Side-striped / Coarse Chameleon (Chamaeleo rudis) from the montane forests on the rim of the Ngorongoro Crater (1800-2000m asl), Conservation Area, Tanzania. February.

Pete Oxford / Galapagos Giant tortoise (Geochelone elephantophus vandenburghi) grazing on rim of crater, Alcedo Volcano, Isabela Island Galapagos islands, Ecuador, South America

Pete Oxford / Galapagos Giant tortoise (Geochelone elephantophus vandenburghi) on rim of crater, with fumaroles behind (emitting steam and gas) Alcedo Volcano, Isabela Island, Galapagos islands, Ecuador, South Amer...

Pete Oxford / Galapagos Giant tortoise (Geochelone elephantophus vandenburghi) on rim of Alcedo Volcano, Isabela Island, Galapagos islands, Ecuador, South America

Tui De Roy / Galapagos Land Iguana (Conolophus subcristatus) on caldera rim, Galapagos Islands, Ecuador

Steven Kazlowski / Common raven (Corvus corax) on south rim of Grand Canyon National Park in winter, Arizona, USA. February.

Steven Kazlowski / Common raven (Corvus corax) on south rim of Grand Canyon National Park in winter, Arizona, USA.

Steven Kazlowski / South rim of the Grand Canyon National Park in winter, Arizona, USA. February 2009.

Steven Kazlowski / South rim of the Grand Canyon National Park in winter, Arizona, USA. February 2009.

Steven Kazlowski / Mule deer (Odocoileus hemionus) large bull on the south rim of the Grand Canyon in snow. Grand Canyon National Park, Arizona, USA.

Wild Wonders of Europe / Radisics / Cala / Arum lily (Zantedeschia aethiopica) flower with water droplets on petal rim, Madeira, March 2009

Matthew Maran / Aerial view of Steller's sealions (Eumetopias jubatus) on rock, Pacific Rim National Park, Vancouver Island, Canada

Matthew Maran / Aerial view of Steller's sealions (Eumetopias jubatus) on rock, Pacific Rim National Park, Vancouver Island, Canada

Matthew Maran / Aerial view of Long Beach, Pacific Rim National Park, Vancouver Island, British Columbia, Canada

Juan Carlos Munoz / Hikers admire the view from the caldera rim of the Chico Volcano, Sierra Negra, Isabela Island, Galapagos, January 2009

Juan Carlos Munoz / Hikers admire the view from the caldera rim of the Chico Volcano, Sierra Negra, Isabela Island, Galapagos, January 2009

Juan Carlos Munoz / Tourists riding horses to the caldera rim of the Chico Volcano, Sierra Negra, Isabela Island, Galapagos, January 2009

Juan Carlos Munoz / View from the caldera rim of Los Gemelos, Santa Cruz Island, Galapagos, January 2009

Juan Carlos Munoz / View from the caldera rim of Los Gemelos, Santa Cruz Island, Galapagos, January 2009

Chris O'Reilly / Common snail (Helix aspersa) on the rim of a plant pot at night, Derbyshire, UK, autumn

Pete Oxford / Two Galapagos giant tortoises (Geochelone elephantophus vandenburghi) on rim of volcano, Alcedo Volcano, Isabela Island, Galapagos Islands

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) portrait, on rim of the Alcedo Volcano, Alcedo Volcano crater floor, Isabela Island, Galapagos Islands

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) on the rim of Alcedo Volcano, Alcedo Volcano crater floor, Isabela Island, Galapagos Islands

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) in long grass on the rim of the Alcedo Volcano, Alcedo Volcano crater floor, Isabela Island, Galapagos Islands

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) in vegetation on the rim of the Alcedo Volcano, Alcedo Volcano crater floor, Isabela Island

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) feeding on the rim of volcano, Alcedo Volcano, Alcedo Volcano crater floor, Isabela Island

Pete Oxford / Galapagos Giant Tortoise (Geochelone elephantophus vandenburghi) on the rim of volcano, Alcedo Volcano, Alcedo Volcano crater floor, Isabela Island

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on rim of volcano, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on rim of volcano, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on rim of volcano, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on rim of volcano, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on rim of volcano, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Pete Oxford / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) on rim of Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Fabio Liverani / Tiny Tree frog {Hyla sp} on rim of tropical fungus, Tambopata National Reserve, Amazonia, Peru

Thomas Marent / Red Rim (Biblis hyperia) butterfly, Colombia

Matthew Maran / Aerial view of The Broken Group Islands, part of the Pacific Rim National Park, Barkely Sound, Vancouver Island, BC, Canada

Matthew Maran / Aerial view of The Broken Group Islands, part of the Pacific Rim National Park, Barkely Sound, Vancouver Island, BC, Canada

Igor Shpilenok / Looking down into the crater lake of the Maly Semyachik Volcano with ice at the rim and azure blue colouring caused by the acidic water, July.

George McCarthy / Brown roll-rim paxillus fungus {Paxillus involutus} UK

Tim Fitzharris / Clearing skies over the South Rim, Grand Canyon National Park, Arizona

Jack Dykinga / South Rim rock formation known as "Duck on a Rock" at sunset, with the "Vishnu Temple" in the background, Grand Canyon NP, Arizona, USA

Jack Dykinga / Snow covered Pinyon Pines (Pinus edulus) overlooking the East Rim Drive, Grand Canyon NP, Arizona, USA

Jack Dykinga / Orange Lichen and Agave (Agave utahensis) on trailside rim rock, South Bass Trail, Grand Canyon NP, Arizona, USA

Jack Dykinga / Snow covered Pinyon Pines (Pinus edulis) overlooking the Grand Canyon, East Rim Drive, Grand Canyon NP, Arizona, USA

Rob Tilley / Sunset over Combers Beach, Pacific Rim National Park, British Columbia, Canada. June 2004

Nick Garbutt / Crater Lodge on rim of Ngorongoro Crater, Tanzania.

Jack Dykinga / Sunrise on stratified rim rock tower at Grandview Point with meandering Colorado River riffle below, Grand Canyon National Park, Arizona, USA.

George McCarthy / View from rim of Grand Canyon, with sedimentary layers obvious, Arizona, USA

Jack Dykinga / Moran Point, South Rim, Grand Canyon National Park, Arizona, USA with scattering of first winter snow.

Jack Dykinga / View of Mt Hayden from Point Imperial, North Rim, Grand Canyon NP, Arizona, USA in afternoon light with rainbow and storm clouds

Jack Dykinga / Kaibab limestone spire, North Kaibab trail, North Rim, Grand Canyon National Park, Arizona, USA with Pinyon pine {Pinus edulis} and Utah juniper {Juniperus osteosperma}

Richard Du Toit / Aerial view of Lesser flamingos {Phoeniconaias minor} on rim of Lake Nakuru, Kenya

Tim Fitzharris / Wotan's Throne from South Rim, Grand Canyon National Park, Arizona

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) dew laden spider webs around fumarole vents, caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcan Alcedo Giant Tortoise (Chelonoidis nigra vandenburghi) large males vie for space in coveted rainy season wallows, caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

JIM CLARE / Aerial view of Cotopaxi volcano crater in snow, Ecuador

Nigel Bean / Cape Royal in evening light, North Rim, Grand Canyon NP, Arizona, USA

HUW CORDEY / View of South Rim, Grand Canyon National Park, Arizona, USA

Doug Allan / Old tree on edge of Bryce Canyon NP, Utah, USA

Doug Wechsler / Looking over rim of Grand Canyon, Grand Canyon NP, Arizona, USA

Pete Oxford / View from rim of cone of active volcano, Sierra Negra, Isabela Is, Galapagos

Tom Vezo / View from Point Sublime of the north rim of the Grand Canyon, Arizona, USA

Pete Oxford / Rocks on rim of cone of active volcano, Sierra Negra, Isabela Is, Galapagos.

Nigel Bean / View across Grand Canyon from South Rim, Arizona, USA.

Pete Oxford / Sulphur crystals from crater of active volcano, Sierra Negra, Isabela Is, Galapagos

Rob Tilley / Ochre / purple seastar {Pisaster ochraceus} Pacific rim NP, BC, Canada

Rob Tilley / Goose barnacles {Pollicipes polymerus} + Mussels, Pacific rim NP, BC, Canada

Rob Tilley / Ochre / purple seastars {Pisaster ochraceus} Pacific rim NP, BC, Canada

Mitsuaki Iwago / Aerial view of Wolf Creek Meteor Crater, approximately 300,000 years old, 25 meters to the rim and 50 meters to the crater floor, north central Australia

Gavin Hellier / Panoramic view of the Grand Canyon from South rim at dusk, Arizona, USA

Gavin Hellier / Panoramic view of South Rim with clearing winter storm, Grand Canyon NP, Arizona, USA

Yva Momatiuk & John Eastcott / Coyote (Canis latrans) illegally fed by tourist in spite of warning signs, Mather Point Parking, South Rim, Grand Canyon National Park, Arizona

Yva Momatiuk & John Eastcott / Tourist depositing plastic bottle into recycling garbage cans in parking lot, South Rim, Grand Canyon National Park, Arizona

Yva Momatiuk & John Eastcott / Recycling garbage cans in parking lot, South Rim, Grand Canyon National Park, Arizona

Tim Fitzharris / Wotans Throne from Cape Royal, North Rim, Grand Canyon National Park, Arizona

Tim Fitzharris / View of the South Rim from Pima Point, Grand Canyon National Park, Arizona

Tim Fitzharris / South Rim of Grand Canyon with a dusting of snow, Grand Canyon National Park, Arizona

Tim Fitzharris / Grand Canyon viewed from North Rim, Grand Canyon National Park, Arizona

Tui De Roy / Galapagos Hawk (Buteo galapagoensis) overlooking sulphur fumaroles on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) searching for water amid steaming fumaroles on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) wallowing in pool at sunrise, caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) amid steaming fumaroles along caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group searching for moisture among steaming fumaroles on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) group searching for moisture among steaming fumaroles on caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) large male on caldera rim, caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) wallowing in temporary rainy season pool, caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Galapagos Giant Tortoise (Chelonoidis nigra) large males on caldera rim, caldera rim, Alcedo Volcano, Isabella Island, Galapagos Islands, Ecuador