Image: Grey Glacier, Chile

Description: This image is a photograph taken by an astronaut aboard the International Space Station, and it captures a striking blue colouration of the glacier. The colouring is due to the ice’s absorption of red wavelengths of light and scattering of blue wavelengths of light as it is transmitted through the ice. Certain portions of the glacier visible in the image are indeed grey. Linear grey-brown moraines are accumulations of soil and rock debris that form along the edges of a glacier as it flows downhill across the landscape (much like a bulldozer blade). Glaciers flowing down slope through adjacent feeder valleys ultimately meet, and debris entrained along their sides becomes concentrated in the central portion of the resulting single, large glacier—much as smaller streams of water join to form a single large river. Three of these medial moraines are visible in the ice mass at image centre left. Gray-brown patches of debris from adjacent mountainsides colour the surface of the easternmost lobe of the glacier (image top). Several crevasse fields are visible in the image. The crevasses, each a small canyon in the ice, form as a result of stress between slower- and faster-moving ice within the glacier. The crevasse patterns of Grey Glacier are complex, perhaps due to the three-lobed nature of its terminus, or end, into Grey Lake. The rugged surface of the glacier is also demonstrated by the jagged shadows it casts onto the surface of the lake. Grey Glacier, like others in southern Patagonia, loses ice from its terminus as it enters the water, a process known as calving. Calving produces large free-floating chunks of ice; some floating ice is visible near the central glacier lobe.
Title: Grey Glacier, Chile
Credit: NASA Earth Observatory
Author: Image provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Laboratory, Johnson Space Center.
Usage Terms: Public domain
License: Public domain
Attribution Required?: No