Fraser Glaciation  
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About 13,000 years ago continental ice from Canada ended its southward journey. Although the high Olympic Mountains blocked its way, ice began skirting around its perimeter leaving gouges, glacial till and other features along the north and east sides of Olympic. The ice dammed many of Olympic's rivers causing great lakes to fill in the interior. Ancient Lake Elwha and Lake Morris are examples. Pleistocene shorelines are found thousands of feet above the river in the Elwha drainage.