Basalt and caliche rock are unique in their prominence of the soils in the grape growing areas . Missoula floods scoured the area stripping the original top soils along the western edge of the Quincy valley . Large standing pools of water left by the floods created thick deposits of caliche that lay over the basalt . With time , both rock types have fractured and are prominent in the soils . Quincy loam and windblown loess soils lay over the rocks
Missoula floods
Missoula Floods
Ancient Lakes of the Columbia Valley AVA