Glacier-filled Kings Canyon. Illustration of the valleys of the Sierra Nevada mountain range three million years ago, filled with glaciers. During this period, the glaciers moved downhill through existing channels eroded by streams and rivers. The heavy weight of the ice carved out the sides of the winding V-shaped river valleys into straight, U-shaped valleys. When the glaciers melted, they left behind wide broad valleys with very steep granite walls. Typical examples are Yosemite Valley and Kings Canyon, the latter valley being part of the Sequoia and Kings Canyon National Parks, California, USA. For the current valleys, see C028/6533 and C028/6534.