This photograph, taken from the International Space Station, shows part of the large glaciated region near the Chilean coast, at a latitude of 47 degrees south. Glaciers consist of moving masses of ice that flow from high altitudes, where snow and ice accumulate, towards lower altitudes, where the ice melts. These glaciers are slowly flowing along deep valleys between mountains. Like the tributaries of a river, confluent valley glaciers flow towards the main glacier and join its flow. The dark stripes are caused by sediment carried in the ice, which becomes smeared out into long bands by the glacier's gradual downhill movement.