dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris. The "U"-shaped cross section of the river valleys are a result of recent glaciation. 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. See also Geography of the North Cascades Geology of the Pacific Northwest Glee Peak References External links Lucinda Davis biography: National Park Service Mountains of Whatcom County, Washington Mountains of Washington (state) North Cascades Cascade Range North Cascades National Park North Cascades of Washington (state) North American 2000 m summits