Brown water flowing from river fed with volcanic silt, Costa Rica

An aerial view of the estuary of the Taw and Torridge Rivers, near Bideford and Barnstaple, Devon, England, United Kingdom, Europe

Holkham Beach, Wells next the Sea, Norfolk, England, United Kingdom, Europe

(Nembrotha spp.) very dark green nudibranch on corals, Mabul, Borneo, Malaysia,

(Nembrotha spp. ) dark and spotted nudibranch on silty seabed, Mabul, Borneo, Malaysia,

Hands break up chunks of soil, Debre Berhan, Ethiopia.

Betsiboka River, Madagascar

Stone-avalanche, damaged cafe, Uerguep, Cappadocia, Turkey

Footprint in tidal mud flats, North Sea, Germany, Europe

Stone-avalanche, Uerguep, Cappadocia, Turkey

Stone-avalanche, damaged cafe, Uerguep, Cappadocia, Turkey

Stone-avalanche, damaged cafe, Uerguep, Cappadocia, Turkey

Stone-avalanche, damaged cafe, Uerguep, Cappadocia, Turkey

Ship for the removal of silt and sand from the harbour bed, in front of Norddeich in the Wadden Sea, Lower Saxony, Germany, Europe

TORRES DEL PAINE NATIONAL PARK, PATAGONIA, CHILE. Hikers enjoy one of the best national parks in South America on a sunny day. With steep peaks full of hanging glaciers and glacial silt-filled lakes, Torres del Paine is one of the greatest attractions on Earth.

TORRES DEL PAINE NATIONAL PARK, PATAGONIA, CHILE. Hikers enjoy one of the best national parks in South America on a sunny day. With steep peaks full of hanging glaciers and glacial silt-filled lakes, Torres del Paine is one of the greatest attractions on Earth.

TORRES DEL PAINE NATIONAL PARK, PATAGONIA, CHILE. Hikers enjoy one of the best national parks in South America on a sunny day. With steep peaks full of hanging glaciers and glacial silt-filled lakes, Torres del Paine is one of the greatest attractions on Earth.

A glacier entering a silty lake, Glacier Bay National Park, Alaska, United States of America

The Pan American Highway is an empty, lonely, desolate road as it runs along Peru's Pacific Desert Coast along the ocean for hundreds of miles, Near Chala, Peru

Small iceberg floating in Greenland's Kaiser Franz Joseph Fjord, East Greenland, Greenland

The silty water of the Tanana River meets the clear water of Clearwater River in Delta Junction, Alaska, United States of America

A group of kayakers paddles on the Tanana River near Delta Junction; Alaska, United States of America

Person walking on the rippled sand at Fano beach, Denmark

People walking on sand at Fano beach, Denmark