Sergey Gorshkov / Tolbachik Volcano erupting, Kamchatka, Russia

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Man studying the geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Linda Pitkin / 2020VISION / Cliffs showing rock striations and geological folding, Pettico Wick, St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, UK, August 2011

David Welling / Dried grasses and red rock geological formations along the Smithsonian Butte National Scenic byway. Southern Utah, USA, July.

Colin Monteath / Clouds covering Lake Coleridge and Rakaia River from Mount Oakden with Mount Hutt on right, Canterbury, New Zealand

Pete Oxford / Devil's Tower National Monument, Wyoming

Tim Fitzharris / Sandstone striations and erosional features, Badlands National Park, South Dakota

Tim Fitzharris / Full moon over the Grand Canyon at sunset as seen from Pima Point, Grand Canyon National Park, Arizona

Tim Fitzharris / View from Grandview Point looking over sandstone canyons of Monument Basin in the Island in the Sky section of the park, Canyonlands National Park, Utah

Gerry Ellis / Soda and algae formations near shore of Lake Natron, Great Rift Valley, Tanzania

Yva Momatiuk & John Eastcott / Toadstool Caprocks created by erosion, near Paria River, Grand Staircase-Escalante National Monument, Utah

Yva Momatiuk & John Eastcott / Grizzly Bear (Ursus arctos horribilis) pair of spring cubs, Denali National Park and Preserve, Alaska

Tim Fitzharris / Temple of the Sun with Sunflowers in the foreground, Capitol Reef National Park, Utah

Jim Brandenburg / Morning Glory pool in Upper Geyser Basin, Yellowstone National Park, Wyoming

Tui De Roy / Cerro Azul caldera with lake and tufa cone at 5,900 feet, Cerro Azul Volcano, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcanic eruption, spatter cone formation and lava fountain from radial fissure, February 1979, Cerro Azul east flank, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcanic eruption, spatter cone formation and lava fountain from radial fissure, February 1979, Cerro Azul east flank, Isabella Island, Galapagos Islands, Ecuador

Tui De Roy / Volcanic eruption, spatter cone formation and lava fountain from radial fissure, February 1979, Cerro Azul east flank, Isabella Island, Galapagos Islands, Ecuador

Sergey Gorshkov / Tolbachik Volcano erupting, Kamchatka, Russia

Tim Fitzharris / Rock formations, Muddy Mountains, Valley of Fire State Park, Nevada

Tim Fitzharris / Sandstone formations, Temples of the Sun and Moon, Capitol Reef National Park, Utah

Tim Fitzharris / Deciduous forest covering mountains, Newfound Gap, Great Smoky Mountains National Park, North Carolina

Tim Fitzharris / Rainbow Vista, Valley of Fire State Park, Nevada

Tim Fitzharris / Gray Rock and White Rock, Garden of the Gods, Colorado

Sergey Gorshkov / Eruption of Tolbachik Volcano, Kamchatka, Russia

Sergey Gorshkov / Lava flow, Tolbachik Volcano, Kamchatka, Russia

Sergey Gorshkov / Eruption of Tolbachik Volcano, Kamchatka, Russia

Sergey Gorshkov / Lava flow, Tolbachik Volcano, Kamchatka, Russia

Sergey Gorshkov / Eruption of Tolbachik Volcano, Kamchatka, Russia

Kevin Schafer / Sandstone sinkhole and rainforest, Buraco das Araras, Mato Grosso do Sul, Pantanal, Brazil

Hiroya Minakuchi / Limestone pinnacles in desert, Nambung National Park, Western Australia, Australia

Colin Monteath / Trekker and limestone ridges with peaks from 4700 meter Cacananpunta Pass, Cordillera Huayhuash, Andes, Peru

Tim Fitzharris / Red Rock Crossing, Arizona

Tim Fitzharris / Tufa at Mono Lake, Sierra Nevada, California

Tim Fitzharris / Rock formation, Monument Valley, Arizona

Tim Fitzharris / Rock formation, Bisti Badlands, Bisti Wilderness Area, New Mexico

Tom Vezo / Lee's Ferry rock formation, Arizona

Tom Vezo / Mushroom hoodoo rock formations, Bisti Wilderness Area, New Mexico

Tom Vezo / Mushroom hoodoo rock formation, Bisti Wilderness Area, New Mexico

Juan Carlos Munoz / Geological rock formations on Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Geological rock formations on Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Man photographing details of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Detail of geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Juan Carlos Munoz / Geological rock formations in the sandstone cliffs of Jaizkibel Beach, Gipuzkoa, Basque Country, Spain, May 2012

Murray Cooper / Layers of earth from past volcanic eruptions, Chimborazo Volcano, Ecuador

Sebastian Kennerknecht / Limestone rocks in dry river bed, Hawf Protected Area, Yemen

Colin Monteath / Folded limestone layers, Kaikoura, North Canterbury, New Zealand

Colin Monteath / Folded limestone layers, Kaikoura, North Canterbury, New Zealand

Pete Oxford / Granite rock formation, Khogno Khan, central Mongolia

Linda Pitkin / 2020VISION / Cliffs showing layers of strata and geological folding, Pettico Wick, St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, UK, August 2011

Linda Pitkin / 2020VISION / Cliffs showing rock striations and geological folding, Pettico Wick, St Abbs (St Abbs and Eyemouth Voluntary Marine Reserve), Berwickshire, Scotland, UK, August 2011

Theo Allofs / Flooded Simpson Desert after heavy rains, Queensland, Australia

Theo Allofs / African Elephant (Loxodonta africana) herd walking in dry river bed, Skeleton Coast, Namib Desert, Namibia

Theo Allofs / African Elephant (Loxodonta africana) herd walking in dry river bed, Skeleton Coast, Namib Desert, Namibia

Theo Allofs / Drought patterns in coastal mud plains, Skeleton Coast, Namib Desert, Namibia

Norbert Wu / Lava and mud flow frozen on barren volcanic crater, Socorro Island, Revillagigedos Islands, Mexico

Piotr Naskrecki / Cliffs, Wolfberg Cracks, Cederberg Wilderness Area, South Africa

Piotr Naskrecki / Katydid (Phyllophora sp) leg with ridges used to produce hissing sound when rubbed against the sternum, Papua New Guinea

Piotr Naskrecki / Stonecrop (Crassulaceae) and rock formation, Brandberg Massif, Namibia

Philippe Clement / The Rock of Falize, a Frasnian limestone anticline (convex geological fold) from the Devonian era. Durbuy, Belgium

Philippe Clement / The Rock of Falize, a Frasnian limestone anticline (convex geological fold) from the Devonian era. Durbuy, Belgium

Konrad Wothe / Granite rock formations, Capo Testa, northern Sardinia, Italy

Konrad Wothe / Granite rock formations, Capo Testa, northern Sardinia, Italy

Konrad Wothe / Granite rock formations, Capo Testa, northern Sardinia, Italy

Colin Monteath / Climber walking on ridge towards Tasman Glacier below Mount Cook, Mount Cook National Park, New Zealand

Christian Ziegler / Limestone formation and Niah Cave, Niah National Park, Sarawak, Malaysia

Ingo Arndt / Nordenskjold Glacier and Allardyce Range, South Georgia Island

Ingo Arndt / Sandstone formation, Utah

Ingo Arndt / Eroded rock formations, Naturpark Pfaelzerwald, Germany

Ingo Arndt / Eroded sandstone hoodoos, Bryce Canyon National Park, Utah

Ingo Arndt / Eroded sandstone hoodoos, Bryce Canyon National Park, Utah

Ingo Arndt / Eroded sandstone hoodoos, Bryce Canyon National Park, Utah

Ingo Arndt / Fire Wave, Valley of Fire State Park, Nevada

David Welling / Summer storm sweeps across Wotan's Throne, Brahma and Zoraster temples and other geological formations. Bright Angel Point on the north rim of Grand Canyon National Park, Arizona, USA, July.

David Welling / Thunderstorms and clouds form over "West Temple" and "Zion" geological formations. Utah, USA, July.

Chien Lee / Mossy-nest Swiftlet (Aerodramus salangana) chicks, less than two weeks old, in nest made on a stalagtite within a limestone cave, Bau, Malaysia

Nick Upton / Eagle's beak (Bec de l'Aigle) conglomerate, puddingstone cliff, near Le Ciotat, France, May 2010

Angelo Gandolfi / Rugged and colourful coast showing geological strata and erosion. Capraia island, National Park of the Tuscany archipelago, Italy, May 2010

Angelo Gandolfi / Rugged and colourful coast showing geological strata and erosion. Capraia island, National Park of the Tuscany archipelago, Italy, May 2010

Angelo Gandolfi / Rugged and colourful coast showing geological strata and erosion. Capraia island, National Park of the Tuscany archipelago, Italy, May 2010

Tim Fitzharris / Sea arch at Pfeiffer Beach, Big Sur, California

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

Tim Fitzharris / Water that has collected in boulder, Joshua Tree National Park, California

Tim Fitzharris / Boulders reflected in lake, Joshua Tree National Park, California

Tim Fitzharris / Sea arch at Pfeiffer Beach, Big Sur, California