Vegetation of the Playa Lakes in the Staked Plains of Western Texas

摘要: The Staked Plains have an altitude of about 3,400 feet above sea-level, and their general slope is southeast south. land surface a plain deposition, little modified, composed sediment carried clown by streams from the Cordilleran region to west in Tertiary Pleistocene tines; is, therefore, comparatively recent. There practically no stream (levelopmnent or drainage, plains are generally flat with scarcely anv irregularities except occasional depressions sales shallow basins containing intermittent lakes known as plavas. These range depth fromt few inches 6o more, circular contour b)owl-shaped smooth slopes. In area they square 400 acres (Iry most year, but contain water for short periods after heavy rainfall. Having outlets, lost 1w evaporation percolation. Geologists advance four theories formation these playas: (i) that solution sinks, (2) remains old courses which been almost filled wind-blown material, (3) due differential settling, (4) formed wind action. Each mav account greater less number playas. Whatever origin, there doubt at present being small amount drainage into them majority soils embraced two series, Amarillo Richfield. soil plavas Ranmall series an(l Randall clay. It sedimientation stirrounding soil, varies front mottled brown rusty clay dark-brown, drab ash-gray Frequently covering fine sandy loam. Greenish gray, friable, calcareous encountered depths 2 6 feet. At 20 contains sufficient lime effervesce acids. dries out color andl often cracks considerable depths. Randally muckv nature andt usually stick tightly auger boring, thus easy remove when neighboring so dry sandyl driller's spoon necessary obtain samples. MNechanical analysis shows gravel, 5 per cent coarse sand, X medium 15, 21 silt, 31