How exactly did the glaciers flatten the Midwestern United States, and was the entire continent mountainous prior to this?

Question

When exactly was this? I have always pictured a giant block of ice slowly sliding diagonally down the middle of the country 🤣

In: 1

Answer 1

It’s the opposite.

The glaciers removed the flat sediments and revealed the non-flat metamorphic and igneous rocks.

Without glaciers, the Canadian Shield would be part of the North American platform and would be flat.

Most of midwestern US wasn’t covered with glaciers, which is why it’s part of the North American platform and is flat. So is the US great plain and the Canadian prairie.