Lake Bassano facts for kids
Lake Bassano was a huge, temporary lake that formed a long, long time ago in what is now south-central Alberta, Canada. This happened during the last Ice Age, when giant glaciers were melting away. As the ice melted, water got trapped, creating this large lake. Lake Bassano was an important part of how the Red Deer River and other rivers in the South Saskatchewan area got their start.
About 7,500 square kilometers (that's a really big area!) of the Bassano region is covered with mud and sand left behind by the lake. These lake sediments are surrounded by higher ground. To the west is the Buffalo Lake Moraine, to the east is the Suffield Moraine, and to the south is the Lethbridge Moraine.
The way water flowed through this area was controlled by the shape of the land and where the edge of the ice was. As the huge Laurentide Ice Sheet (a giant glacier) melted and moved back, lower paths for water opened up. The water level of the lake at any time depended on the height of the lowest path where water could flow out. As Glacial Lake Bassano and other lakes like it formed, the water flow in different channels would grow, shrink, or even reverse direction, depending on how the ice and land changed.
How Glacial Lakes Formed
When the huge Laurentide Ice Sheet melted and moved back in Alberta, it left behind large areas of lake sediments. These lakes formed because melting ice and existing rivers got blocked by the glacier. One expert, Quigley (1980), guessed that about half of Alberta was once covered by these temporary lakes.
By mapping the mud and sand left by these lakes, scientists can figure out where the edge of the glacier was at different times as it melted. Early studies of these lakes in southern Alberta had problems because they didn't have exact height measurements. Later studies lacked good ways to tell the exact age of things. Also, there wasn't a detailed study showing how all these different glacial lakes in southern Alberta were connected. But by carefully looking at the land's shape, scientists can now figure out the order in which these lakes formed and drained. They can also find their highest and lowest water levels.
Water Flow and Lake Levels
In southern Alberta, the network of glacial lakes slowly got lower as the Laurentide Ice Sheet melted and moved back. The highest lake, Glacial Lake McLeod, was at about 1100 meters (about 3,600 feet) above sea level. The lowest was Glacial Lake Empress, at about 680 meters (about 2,230 feet).
Water from Glacial Lakes Drumheller, Gleichen, and Lethbridge all joined up. This water then flowed through a channel called Etzikom Coulee into the Missouri River system. When Etzikom Coulee was no longer used (at 915 meters or about 3,000 feet high), all the water from these lakes stayed within Alberta.
Glacial Lake Drumheller stopped flowing through the Strathmore Channel when it was 945 meters (about 3,100 feet) high. Then, the water flowed through a smaller channel called Crowfoot until it reached 915 meters. At this height, the water must have moved further east, flowing over the Bassano area. Glacial Lake Gleichen stopped flowing south through the McGregor Lake Channel at 860 meters (about 2,820 feet). It then flowed eastward into Glacial Lake Bassano until a river channel formed at 850 meters (about 2,790 feet).
As the ice melted further, Glacial Lake Lethbridge got lower and spread eastward. This formed Glacial Lake Taber. Its upper water level was controlled by Chin Coulee (915 meters). Later, water flowed through Forty Mile Coulee until it reached 792 meters (about 2,600 feet). It then flowed along the valley of the South Saskatchewan River, which became a clear river channel at 760 meters (about 2,500 feet). Glacial Lake Medicine Hat formed at about 760 meters. Water pooling there was connected to Glacial Lake Empress forming to the north, at about the same height.
Glacial Lake Bassano existed from a highest level of 915 meters until it finally drained away at 690-700 meters (about 2,260-2,300 feet). Its beginning happened when water stopped flowing south into the Missouri River system. This also marked the start of all the water flowing within Alberta. Along with Glacial Lake Tilley to the south, Glacial Lake Bassano received water from over 1,000 kilometers (about 620 miles) of the melting Laurentide Ice Sheet and other nearby glacial lakes.
