Artistic interventions in "America's Attic" indicate the region's importance to the geographical, ethnic and cultural history of the American Southwest As the largest alpine valley in the world, Colorado's San Luis Valley is a land of sand dunes, wetlands and farmland--nearly all of it above 8,000 feet in elevation and all within a footprint of roughly 150 by 75 miles. Only sparsely covered by historians and geoscientists,...