 Today the topsoil found throughout the Columbia Valley is mostly sandy and stone-studded on top of basalt-based soil foundation created by persistent lava.These sandy loam vineyard soils create a nearly inhospitable environment for the phylloxera louse, which may be one of the reasons why the phylloxera epidemic has not ravaged the Washington wine industry as it has the Californian and French wine industries in the past.The state's northerly location above the 46th parallel north allows Washington's major wine growing regions to experience 17 hours of sunlight in the summer—two more hours of sunlight during the peak of growing season than what California sees further south.