The Rocks District of Milton-Freewater is wholly contained within both Walla Walla Valley and Columbia Valley AVAs and is found in northeastern Oregon, 25 miles northeast of Pendleton and five miles south of Walla Walla, WA. The unique soils of The Rocks District of Milton-Freewater are its defining characteristic. They consist of pebbles and cobbles of basalt (dark volcanic rock) in a matrix of sand and silt. The rocky soil is extremely well drained, encouraging the vines to root deeply, and the dark rocks efficiently transfer heat into the soils and radiate heat to the ripening grapes. The Rocks District is the only AVA in the United States whose boundaries were determined by a single land form and a single soil series.