“The icy grip of continental glaciers was one of the most significant geologic processes to affect the Iowa landscape. Most of the deposits underlying today’s land surface are composed of material known as till that was moved here by glaciers.”
Jean Prior, 1991
Landforms of Iowa, 1991.
The Three Rivers Trail is contained within the Iowa landform known as the Des Moines Lobe. This part of Iowa was most recently covered by glaciers.
From 2 million years ago to 12,000 years ago, glaciers advanced and retreated over all of Iowa. The Des Moines Lobe is the location of the most recent glaciation.
Imagine the Des Moines River as wide as the Mississippi. Imagine wooly mammoths and saber tooth cats living at the foot of an ice sheet that extended to what must have seemed like the ends of earth to the north. Instead of endless sky, a spruce forest. Instead of sedate, meandering streams, torrential rivers that deposited rocks the size of your head a mile from the glacier. This was the world of the melting glaciers in the location of the Three Rivers Trail.