Wallowa Lake

Oregon Geology Wallowa Lake Wallowa Lake Fills a depression that was formerly occupied by a great river of ice that flowed out of the high Wallowa Mountains to the South. This Glacier reached its greatest size in the late Pleistocene age about 12 to 40 thousand years ago. As it flowed out onto the valley floor, the glacier built great piles of rock debris around its edges, called moraines. When the ice melted away, the moraines remained as the high straight ridges we see today. The lake is 283 feet deep, but the glacier was over 1500 feet thick. These moraines are some of the best-preserved examples to be found anywhere in North America.