Running Water
"Put more water for channels there and with that stick mark where that channel and river are gonna run." - Crow Makes the World as told by Louise Profeit-Leblanc
Glacial meltwater streams flowing off the Kaskawulsh glacier. Photo:
Charlie Roots
Running water carves and shapes the land.
During the last glacial age, creeks and rivers fed by glacial meltwater carved extensive valley systems. These valley systems were reshaped repeatedly as the glaciers melted and expanded. The Yukon River that flows northwest through Whitehorse used to flow south. At the beginning of the last glacial age, the Cordilleran ice flowing from the south and the east blocked the flow of the river forcing it to flow north. Many major rivers were diverted by the ice flow.
Plants and animals thrive along riverbanks.
The sand in the dry creekbed to the left settled out of the slower moving water that flowed on the inside bend of the creek. Smaller particles were washed away from the larger rocks in the faster, outside channel, under the bank. The inside bends of creeks are often rich in plant life because of the nutrient-rich particles dropped there by flowing water. The warming effect of running water also lowers permafrost levels on inside bends.
Meandering river on the North Slope, Yukon. The richer vegetation (darker green)
is found on inside bends. Photo: Government of Yukon
Rivers provide refuge and transport in rough times.
During periods of glaciation, river valleys could support a few tree and shrub browsers like mastodon, even when the surrounding grasslands could not. The Yukon River drainage also supported many fish, such as arctic grayling and lake whitefish. During warmer interglacial periods, plants spreading north used rivers to spread their seeds.
As the climate warms, more precipitation is expected in the Canadian north, but higher temperatures could evaporate much of that moisture, leaving the Yukon even drier than it already is.