Tuesday, July 7, 2015  Dan McShane

Haystack rock south of Highway 2 on the Waterville Plateau This large boulder marks the approximate southernmost reach of glacial ice.

The farthest south extent of the continental ice in central Washington during the ice age was the Okanogan ice lobe. The ice flowed down the Okanogan valley blocked the Columbia River and extended south across the Waterville Plateau.

This ice lobe and its associated blockage of the Columbia River has led to a cluster of five landforms that have been listed as National Natural Landmarks on or at the edges of the Waterville Plateau. One of those features is the huge deflation gravel bar in Mosses Coulee crossed by Highway 2 west of the picture above (huge-deflation-bar-at-moses-coulee). […]