Giant current ripples atop a kame terrace surface near Omak, WA. Hwy 20 is at the center of the image.
The ripples are of similar scale to those found at classic Missoula flood localities such as Camas Prairie, MT. They were produced by a down-valley flood. The specific source of the water is not known, only that it came from somewhere to the north. Floodwater may have been spilled from beneath the Cordilleran Ice Sheet and flowed down the Okanogan Valley (i.e., Lesemann and Brenand, 2009) or from a local tributary canyon (i.e., Russell, 1898; Dawson, 1898; Waters, 1933). An outburst flood spilled from nearby Johnson Creek covered the Pogue Flat/Omak Airport area in coarse boulder gravel.
The Okanogan Valley contains an extensive kame terrace system - the preserved record of enormous volumes of water (mostly ice marginal streams) and sediment moving along the margin of downwasting Okanogan Lobe during glacial retreat at the end of the last Ice Age.