Jack Dykinga / Valle de la Luna, The Codillera de Sal, formed by layer upon layer of salt, sand and clay, creating strata that buckled with earth's crust and lined with sand dunes. Atacama Desert, Chile. April 2009

Chadden Hunter / Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, in the bottom of the Rift Valley, 120 me...

Wild Wonders of Europe / Lundgren / Blue rayed limpet (Patina / Ansates pellucida) on seaweed with Sea-mat / Lacy crust bryozoan (Membranipora membranacea) on shell, Saltstraumen, Bod, Norway, October 2008

Wild Wonders of Europe / Lundgren / Blue rayed limpet (Patina / Ansates pellucida) with Sea-mat / Lacy crust bryozoan (Membranipora membranacea) growing on shell, Saltstraumen, Bod, Norway, October 2008

Wild Wonders of Europe / Lundgren / Three Nudibranchs (Polycera quadrilineata) on Kelp encrusted with Sea-mat / Lacy crust bryozoan (Membranipora membranacea) Saltstraumen, Bod, Norway, October 2008

Owen Newman / Soda crust on Lake Natron, Tanzania, coloured red by alkali cyanobacteria, breeding site of endangered Lesser Flamingo

Richard Du Toit / African elephant sprays itself with mud {Loxodonta africana} Linyanti, Botswana, Southern Africa. The mud-pack, when dry, forms a hard crust that deters insect attacks.

Jean E. Roche / Aerial view of crystallisation of salt in a depression, Aigues-mortes saltpans, Camargue, Southern France, August 2008

Jean E. Roche / Aerial view of crystallisation of salt in a depression, Aigues-mortes saltpans, Camargue, Southern France, August 2008

Jean E. Roche / Aerial view of concentrated salt pans with salt crust, Salins de Giraud, Camargue, Southern France

Jean E. Roche / Aerial view of salt crust on salt pan, Aigues-Mortes, Camargue, Southern France

Jean E. Roche / Aerial view of crystallisation of salt in a lagoon depression, Aigues-mortes saltpans, Camargue, Southern France, August 2008

Jean E. Roche / Aerial view of dry lagoon with salt crust in marshes, Camargue, southern France, June 2007

Juan Carlos Munoz / Aerial view of Lake Magadi with patterns created by saline crust, Rift Valley, Kenya, August 2009

Juan Carlos Munoz / Aerial view of salt crust on Lake Magadi in the Rift Valley, Kenya, August 2009

Thomas Lazar / Close-up of petrified rock log chips on dried and cracking crust, Petrified Forest National Park, Arizona, USA, March 2008

Chadden Hunter / Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, in the bottom of the Rift Valley, 120 me...

Chadden Hunter / Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, in the bottom of the Rift Valley, 120 me...

Chadden Hunter / Cameraman, Martyn Colbeck, filming the Dallol hot springs where water heated by magma laden with potassium, sulphur and iron spews up through salt pans staining the salt deposits with vivid colours, i...

Robert Thompson / Toothed crust lichen {Hyphoderma radula} on fallen chestnut branch, Castle Coole, County Fermanagh, Northern Ireland, UK

Wild Wonders of Europe / Lundgren / Nudibranchs (Polycera quadrilineata) mating on Sea-mat / Lacy crust bryozoan (Membranipora membranacea) Moere coastline, Norway, February 2009

Wild Wonders of Europe / Lundgren / Common hermit crab (Pagurus barnharudus) on Kelp with Sea-mat / Lacy crust bryozoan (Membranipora membranacea) growing on it, Lofoten, Norway, November 2008

Wild Wonders of Europe / Lundgren / Nudibranch (Polycera quadrilineata) on Sea-mat / Lacy crust bryozoan (Membranipora membranacea)Lofoten, Norway, November 2008

Wild Wonders of Europe / Lundgren / Skeleton shrimp (Caprellidea sp) on a hydroid on Sea-mat / Lacy crust bryozoan (Membranipora membranacea), Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Blue rayed limpet (Patina / Ansates pellucida) on seaweed with Sea-mat / Lacy crust bryozoan (Membranipora membranacea) on shell, Saltstraumen, Bodø, Norway, October 2008

Wild Wonders of Europe / Lundgren / Skeleton shrimp (Caprellidea sp) on Sea-mat / Lacy crust bryozoan (Membranipora membranacea)Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Skeleton shrimp (Caprellidea sp) on a hydroid on Sea-mat / Lacy crust bryozoan (Membranipora membranacea) Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Banded chink shell (Lacuna vincta) on Sea-mat / Lacy crust bryozoan (Membranipora membranacea) Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Nudibranchs (Polycera quadrilineata) and Moss animals on Sea-mat / Lacy crust bryozoan (Membranipora membranacea), Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Nudibranch (Dendronotus frondosus) on Sea-mat / Lacy crust bryozoan (Membranipora membranacea)Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Blue rayed limpet (Patina / Ansates pellucida) with Sea-mat / Lacy crust bryozoan (Membranipora membranacea) growing on shell, Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Two skeleton shrimps (Caprellidea sp) on Sea-mat / Lacy crust bryozoan (Membranipora membranacea)Saltstraumen, Bodö, Norway, October 2008

Wild Wonders of Europe / Lundgren / Skeleton shrimp (Caprellidea sp) on a hydroid on Sea-mat / Lacy crust bryozoan (Membranipora membranacea) Saltstraumen, Bodö, Norway, October 2008 Wild Wonders kids book.

Richard Du Toit / Soda and algae crust on Lake Natron, Tanzania

Richard Du Toit / Patterns in alkaline salt crust on surface of Lake Natron, Tanzania

Owen Newman / Soda crust on Lake Natron, Tanzania, coloured red by alkali cyanobacteria

Owen Newman / Soda crust on Lake Natron, Tanzania, coloured red by alkali cyanobacteria

Nick Upton / Crushed and uplifted earth crust at epicentre of earthquake, nr Puli, Taiwan

Paul D Stewart / Illustration frontispiece from Thomas Burnet's 'The Sacred Theory of the Earth' 1684, the most popular geological work of the 17th century. Christ stands aside the full cycle of creation with the epit...

Paul D Stewart / Illustration with later hand colouring from Thomas Burnet's 'The Sacred Theory of the Earth' 1684. In it he postulates how the 'perfect' featureless earth of the creation is transformed by waters unle...

Paul D Stewart / Illustration with later hand colouring from Thomas Burnet's 'The Sacred Theory of the Earth' 1684. In it he postulates how the 'perfect' featureless earth of the creation is transformed by waters unle...

John Cancalosi / Galena (PbS, lead sulfide), the primary ore of lead, on Quartz (SiO2), the most common mineral in the Earth's crust. Sample from Madan, Bulgaria.

John Cancalosi / Muscovite (Mica), one of the most common minerals in the earth's crust, having wide economic importance. Sample from Minas Gerais, Brazil.