This region was produced when fissures in the Earth's crust caused a rift valley, which is defined as a "valley formed when the section of land between the cracks in the Earth's crust sinks down." This landform area has two main waterways: the St. Lawrence River and Lake Huron. The river itself is over 1000 miles long and flows into the Atlantic Ocean.
The Saint Lawrence River forms in the northern part of New York state and travels nearly 1,000 miles through five different states before reaching the Atlantic Ocean. The river is known for its size and is one of the largest rivers in North America. It has three major tributaries: the Ottawa River, Hudson River, and Niagara River.
The source of the Saint Lawrence River is located in Quebec, Canada. There are two main theories on how this region was created. One theory says that the river was formed when a large slab of ice broke off from the Great Lakes and crashed into the surrounding rock causing a fracture that would eventually become the river. The other theory says that the river was formed when South America and Africa collided with each other creating a trench that the ocean drained into. This left a gap in the center of the continent which eventually became what is now the Saint Lawrence Valley.
After it is formed, the Saint Lawrence River passes through four major cities before reaching the Atlantic Ocean: Montreal, Quebec; Toronto, Ontario; Windsor, Ontario; and Lewiston, New York.
Although multiple geological phenomena account for the production of countless lakes on Earth, glacier action is responsible for the majority of lake formation. Lakes may be formed through the movement of earth, water, and wind. Folds, tilts, and sinking of the earth's crust occur as rock deformations, commonly along fault lines. These changes can cause one portion of the crust to dip below another, resulting in sunken areas that fill with water. This process often creates deep wells that reach groundwater levels or even beyond. On landforms called shields, linear ridges run perpendicular to the direction of the fold. As the shield rises toward the sky, so does its side, leading to the appearance of a taco-shaped hole when viewed from above. The shallow end of this hole is where surface waters drain into the hollow core.
Lakes can also form as a result of volcanic activity. A large volume of water vapor is given off whenever molten rock cools down. If this cooling occurs near the ground, liquid lava may well surface to form a new lake. Volcanoes may also blow their tops off, sending hot gas and debris into the air. Water from precipitation falls as rain or snow, filling any empty spaces between these particles of dust and ash. When enough water has accumulated, it will flow over the top and freeze into a glacial ice field or glacier.
Finally, lakes can arise from the melting of snow or ice.
Volcanic rifts generated the geological structures under Lakes Superior and Ontario. Their canyon walls are made of soft basalt and reach a depth of 1300 feet below sea level. The Welland Canal allows ships to navigate the Niagara Peninsula's escarpment between Lake Erie and Lake Ontario. It was built by prisoners using shovels and picks made from frozen trees.
The canal starts near Lake Erie at a point where the Niagara River exits through a narrow channel called Port Dalgarno. It passes beneath a large artificial harbor called Port Colborne, then continues on into Lake Ontario at Fort William. The canal cuts through the rugged cliffs that form the border between Canada and New York State. At its deepest, it is 1 mile (1.6 km) wide and 30 feet (9 m) deep.
The canal was built as an alternative route for shipping goods between the Great Lakes and the Atlantic Ocean. When it opened in 1829, it was the longest canal in the world. But despite its success, it wasn't enough to make either Port Colborne or Fort William profitable. So in 1880, they were closed to commercial traffic and turned over to the Canadian National Railway. Today, the canal is used by recreational boats and provides a link between the lakes and the Saint Lawrence Seaway.
In addition to its role in shipping, the canal has had an impact on the landscape itself.