During the last Ice Age, nearly all of Canada was covered by massive ice sheets. Thousands of years later, the landscape of Nunavut Territory (“our land” in the Inuktitut language) still shows the scars of that icy earth mover. NASA Earth Observatory image by Robert Simmon
The image above shows wetlands in the Kitikmeot region of Nunavut Territory, just east of the Queen Maud Gulf Bird Sanctuary and southwest of the village of Gjoa Haven.
Surfaces that were scoured by retreating ice and then flooded by Arctic seas are now dotted with millions of lakes, ponds, and streams.
The image was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (http://wordlesstech.com/2010/10/21/alaska-susitna-glacier/
) on NASA’s Terra satellite on July 18, 2001. ASTER combines 14 spectral bands in infrared, red, and green wavelengths of light to make false-color images. Water is various shades of blue, green, tan, and black, depending on the amount of suspended sediment (silt and clay) and phytoplankton. Vegetated land is red.
These Arctic lowlands are covered by long, low-rising ridges of glacial till—a mixture of clay, sand, gravel and boulders. “These small hills were glacially moulded by ice as the ice sheet moved to the north,” said Daniel Kerr of the Geological Survey of Canada. “This area became ice-free by about 8,000 years ago, but because of the weight of the ice sheet, the land was depressed and the waters of the Arctic Ocean flooded the land.” Those hills are surrounded by small valleys and flatlands of marine silts and clays, which were deposited by the sea before it retreated and the land surface rose back up (a process known as isostatic rebound).
NASA Earth Observatory image by Robert Simmon, using data from the NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Michael Carlowicz, with image interpretation by Daniel Kerr, Geological Survey of Canada.