The Great Lakes have many small rivers that flow into them, and they are all connected and flow from one to the next. The rivers flowing into them begin on higher ground where rainwater, melting ice and snow and natural springs feed them.
There are five Great Lakes, and out of the five, four are partly in Canada (Lake Superior, Lake Huron, Lake Erie and Lake Ontario). They are some of the biggest freshwater lakes in the world and contain 20 percent of the world’s fresh water. Unfortunately we haven’t been very careful to keep this water fresh and clean in the past, although people recognize now that it is a problem that needs to be fixed.
The waters of the Great Lakes begin with those which flow into Lake Superior. This lake is the largest and the highest. It is also the deepest being almost a quarter mile deep. It is fed by water that flows from Lake Nipigon through the Nipigon River as well as snow and rain. It’s shores are heavily wooded and rocky. The north shore has sheer, rocky cliffs up to 305 metres high. Near Thunder Bay there is a ridge of rock 300 metres high and 33 kilometres long that looks like a sleeping giant. It’s water flows out through St. Mary’s River into Lake Huron through a series of gates which control the flow and keep the lake at not more than 183 metres above sea level.
Manitoulin Island, the biggest island in a freshwater lake in the world, is in Lake Huron. This lake is connected to the next great lake (Erie) by a small lake called Lake St. Clair and it is also connected to Lake Michigan which is in the United States.
Lake Erie is the shallowest lake. It’s water warms up quickly. It is connected to the next lake by the biggest drop in height at Niagara Falls!
By the time this water reaches Lake Ontario, the final lake, it is at 74 metres above sea level. The water then flows into the St. Lawrence River, which flows out into the Atlantic Ocean.
Human actions have damaged these lakes. Loggers choked up the streams that flow into Lake Superior and sawmills polluted the bays with sawdust and wood waste. This destroyed spawning areas for many fish. The canal built to bypass Niagara Falls and allow ships into the Great Lakes, also brought non-native creatures such as sea lampreys which attach themselves to fish and kill them. Pesticides and wastes from industries have polluted the lakes and caused problems with the native wildlife.
Activity: Read Paddle to the Sea by Holling C. Holling, 1969. This is the story of a little canoe carved out of wood by a boy and set on a journey from Lake Nipigon to the Atlantic Ocean. Draw out a map of the Great Lakes – there is a map to copy in the back of the book – and follow Paddle’s journey on this map as you read. Take notes of what he sees and does along the way. This blog has some great notebooking pages: Butterflies & Barefoot Lasses.
ARTICLES: Human impact on the great lakes.