[5] The history of the formation of the Cascade Mountains dates back millions of years ago to the late Eocene Epoch.

[6] In addition, small fragments of the oceanic and continental lithosphere called terranes created the North Cascades about 50 million years ago.

[6] During the Pleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape.

Uplift and faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the North Cascades area.

As a result, the Cascade Mountains experience high precipitation, especially during the winter months in the form of snowfall.