Glaciation and The Great Lakes
How the glaciers shaped the Great Lakes as we know them today.
Topographic map pointing out each of the Great Lakes.
A Brief Overview
Around 20,000 years ago, ice sculpted the landscape of North America. These glaciers carved out some of the largest freshwater lakes on the planet: the Great Lakes!
Let's explore how glaciers form and move, the landforms and features that they create, and most importantly, their role in the creation of the Great Lakes!
What Are Glaciers?
In their most simple definition, glaciers are thick masses of ice that originate on land.
Types of Glaciers:
There are two broad categories of glaciers: Alpine Glaciers and Continental Glaciers. With different glacier types, we see different landforms and topographic features!
Photo of alpine glaciers in mountain valleys.
Alpine Glaciers
Model of an Alpine Glacier and it's parts.
- Found in mountainous regions
- move slowly downslope
- smaller in size
- snow and ice continuously replenished from surrounding mountains
- carve valleys and other small landforms
Alpine Glaciers: Landforms
Continental Glaciers
The second type of glacier is a continental glacier!
- very large ice sheets
- can cover entire continents
- formed in colder climates
- can alter entire landscapes
Photo of a continental glacier.
The Great Lakes (Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario) are erosional features created by continental glaciers! We owe these lakes largely to one glacier in particular... the Laurentide ice sheet.
The Laurentide Ice Sheet
Map of the Laurentide Ice Sheet over Canada and much of the Northern United States.
The Laurentide ice sheet was up to two miles thick at its thickest part but was much thinner at the edges. As it advanced and melted in cycles, it scoured and eroded glacial landforms including the Great Lakes.
*This is an example of a continental glacier!
Progression of the Laurentide Ice Sheet carving out the great lakes over time.
Glacial Landforms in the Great Lakes Region
The topographic features that are seen in the Great Lakes region are landforms characteristic of continental glaciers. These landforms include erosional features like finger lakes and roche moutonnee, depositional landforms like moraines, drumlins, and flutes, and stagnant glacial landforms like eskers, kames, kettles, and outwash plains.
Human Connection & Environmental Impact
When it comes to impact on humans and the environment, the Great Lakes have a lot to offer! These lakes help with...
One of the lakes being used for recreational activities!
- air and water purification
- controlling temperature
- providing fresh water
- food production
- soil fertility
- local biodiversity
On top of this, these lakes contribute to the region's scenic landscape and are important for recreation and tourism.
Conclusion
The Great Lakes are more than just vast bodies of water, they're reminders of an ancient glacial past!
Formed by the advance and retreat of ice, they are incredible examples of the power of glaciers and contain many beautiful examples of glacially created landforms. These lakes continue to influence the environment and human life today and give us insight to our geologic past.
