Credit:
BERNHARD EDMAIER / SCIENCE PHOTO LIBRARY

CREDIT MUST BE GIVEN IN FULL

Caption
Stream, Iceland. Aerial view of a stream flowing from top right to bottom left over black volcanic sand in south Iceland. A bank of vegetation is seen lower right. The stream originates from marshland and is acidic. The acid reacts with the black volcanic sand which precipitates iron and colours the water yellow. At the dry edges of the stream, the iron has formed iron oxide, which is rusty brown in colour. The stream flows into the River Thjorsa, which flows into the Atlantic Ocean.