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REGION 11: THE SANDY SOUTH PLAINS

As the title indicates, this region is characterized by deep sand. Under the force of strong winds the sand has been piled into dunes, most of which have become stabilized by vegetation. Some, however, are still sufficiently bare to permit the wind to blow the loose sand. These are blowing dunes. Even on stabilized areas, railway and highway rights-of-way have to be protected against wind action in order to prevent burial of track or pavement.

Shallow basins occur from which there are no drainage outlets. Rain comes comparatively seldom; but, when it does come, in a large percentage of cases it comes in deluge proportions. Run-off from the slopes collects in the depressions, bringing along a solution of the alkaline salts with which the soil is impregnated. Recurrent evaporation through the years has produced the famous salt lakes, which under normal conditions have a shallow, concentrated liquid center surrounded by a bordering zone of crusted, snowy white, precipitated salts. Outside this zone the first vegetation appears in the form of fleshy leaved, succulent herbs, salt grass and salt cedar. On the adjacent slopes salinity rapidly decreases and vegetation assumes the character normal to sandy soil in a semi-arid, south-temperate climate. Drop-seed grasses, Mullenbergias, triple-awn grass, squirrel-tail, burro grass and tobosa are more or less intermixed with the more nutritious bluestems (Andropogon spp.) and gramas. Buffalo and curly mesquite grass are confined to tighter, finer textured soils; hence, are rare in this region.

Wild flowers are plentiful when rains give them a chance to grow. Mustards, morning-glory, borage, four o'clocks, western jimson-weed, fox-gloves and a wealth of blue, white, and yellow composites combine to give the landscape in bloom a gala array of color.

Upland shrubs are principally mimosas, acacias, mesquites, and, in certain areas, vast stretches of Havard's midget oak (Quercus havardii). The last named, on level or gently undulating areas, is frequently dense in stand and intermixed with little bluestem and