lithosphere called terranes created the North Cascades about 50 million years ago. During the Pleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured and shaped the landscape. A small glacial remnant lies on the south slope of Dorado Needle, whereas the northern slope maintains the extensive McAllister Glacier. 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. References External links Luna Peak photo: Flickr Mountains of Washington (state) North Cascades of Washington (state) Mountains of Whatcom County, Washington North Cascades National Park hu:Luna Peak