The arid Salt Shrub Valleys were once inundated by Pleistocene lakes. Nearly flat basin floors are extensive and wetlands, terraces, dunes, and alluvial fans also occur. Characteristically, the basin floors have strongly saline and very alkaline soils that support black greasewood, inland saltgrass, shadscale, and bud sagebrush. Soils, climate, and vegetation are transitional to the Central Basin and Range and Lahontan Salt Shrub Basin to the south. Rangeland and irrigated agriculture occur.
Thorson, T.D., Bryce, S.A., Lammers, D.A., Woods, A.J., Omernik, J.M., Kagan, J., Pater, D.E., and Comstock, J.A., 2003. Ecoregions of Oregon (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,500,000).