Silurian Valley - Devil’s Playground

This subsection includes the alluvial plain of the Silurian Valley, from where the Amargosa River enters it on the north to where the Mojave River enters it on the south, and the Devil’s Playground just southeast of Silurian Valley and up Kelso Wash toward Ivanpah Valley.  There are a few hills protruding through the alluvial plain.  It has a very hot, arid climate.  MLRA 30g.

Lithology and Stratigraphy.  This subsection contains mainly Quaternary fluvial, lacustrine, and eolian sand deposits.  Hills protruding through the alluvial plain are mostly Mesozoic granitic, Paleozoic marine, and Precambrian metamorphic rocks.

Geomorphology.   This subsection is mainly on very gently to moderately sloping alluvial fans, nearly level basin floor and dry lake bed, and sloping to steep sand dunes.  There are large playas on Soda Lake, Silver Lake, and Silurian Lake.  The elevation range is about 300 to 1200 feet on alluvial plains and up to about 2400 feet on the highest hill.  Fluvial erosion and deposition and eolian deflation and deposition are the main geomorphic processes.

Soils.  The soils are mostly Typic subgroups of Torrifluvents, Torripsamments, and Torriorthents on younger fans and basin-fill and Typic subgroups of Torriorthents, Calciorthids, Camborthids, and Haplargids on older fans.  Soils on hills are mostly Lithic Torriorthents, plus Lithic Camborthids on granitic rocks.  Soils on dune sand are Typic Torripsamments.  The soils are well drained, except on poorly drained playas.  Soil temperature regimes are hyperthermic; and soil moisture regimes are aridic.

Vegetation.   The predominant natural plant community is Creosote bush series on hills and fans.  Mixed saltbush series is common on basin floor and Iodine bush series and Saltgrass series are present on wet basin-fill and lacustrine deposits.  The Desert sand - verbena series is common on stabilized dunes.

Characteristic series by lifeform include:

Grasslands: Alkali sacaton series, Big galleta series, Desert sand - verbena series, Indian ricegrass series, Saltgrass series.

Shrublands: Brittlebrush series, Creosote bush series, Creosote bush - white bursage series, Desert-holly series, Fourwing saltbrush series, Greasewood series, Iodine bush series, Joshua tree series, Mixed saltbush series, Scadscale series, White bursage series, Winter fat series.

Forests and woodlands: Mesquite series.

Surface Water.  Runoff is rapid from mountains and alluvial fans and slow from basin-fill.  All drainage is internal, to closed basins in Silurian Valley or in Death Valley. Some water from the Mojave River, reaches Soda Lake in wet years, even though it might not flow overland (above-ground).  During the Pleistocene the Mojave and Amargosa Rivers drained through Silurian Valley to Death Valley.   Streams are dry most of each year.  There is temporary ponding on playas, or dry lake beds.