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J.M. Sowers

Publications and source records attributed to J.M. Sowers.

5 recordsLinked to original sources
USGS2017

Rates of soil development from four soil chronosequences in the southern Great Basin

Four soil chronosequences in the southern Great Basin were examined in order to study and quantify soil development during the Quaternary. Soils of all four areas are developed in gravelly alluvial fans in semiarid climates with 8 to 40 cm mean annual precipitation. Lithologies of alluvium are granite-gneiss at Silver Lake, granite and basalt at Cima Volcanic Field, limestone at Kyle Canyon, and siliceous volcanic rocks at Fortymile Wash. Ages of the soils are approximated from several radiometric and experimental techniques, and rates are assessed using a conservative mathematical approach. Average rates for Holocene soils at Silver Lake are about 10 times higher than for Pleistocene soils at Kyle Canyon and Fortymile Wash, based on limited age control. Holocene soils in all four areas appear to develop at similar rates, and Pleistocene soils at Kyle Canyon and Fortymile Wash may differ by only a factor of 2 to 4. Over time spans of several millennia, a preferred model for the age curves is not linear but may be exponential or parabolic, in which rates decrease with increasing age. These preliminary results imply that the geographical variation in rates within the southern Great Basin-Mojave region may be much less significant than temporal variation in rates of soil development. The reasons for temporal variation in rates and processes of soil development are complexly linked to climatic change and related changes in water and dust, erosional history, and internally driven chemical and physical processes. ?? 1991.

Quaternary Research↗
USGS1992

Morphology and genesis of carbonate soils on the Kyle Canyon fan, Nevada, U.S.A.

The physical and chemical properties of soils formed in an arid climate on calcareous alluvium of the Kyle Canyon alluvial fan, southern Nevada, were studied in order to infer the rates and relative importance of various soil-forming processes. These studies included field and microscopic observations and analyses of thin sections, major oxides, extractable iron, and clay minerals. The results are interpreted to reflect five major pedogenic processes: (1) The calcic horizons and calcretes of Kyle Canyon soils form by precipitation of CaCO 3 , derived from eolian dust and alluvium, as clast coats, matrix cement, and massive layers. (2) The A and uppermost B horizons are essentially dust-derived, for they contain large amounts of detrital material not present in the alluvial parent material, and their major-oxide content is similar to that of modern dust. (3) Clay particles are translocated from A into B horizons. (4) Iron-bearing minerals in the near-surface B horizons are slowly oxidized. (5) Carbonate and aluminosilicate grains are both displaced and replaced by pedogenic CaCO 3 ; the silica released by replacement of aluminosilicates may be locally precipitated as amorphous or opaline silica and (or) incorporated into newly formed palygorskite and sepiolite. Rates of soil development at Kyle Canyon are approximate due to uncertainties in age estimates. Some soil field properties change at rates that are similar to rates for soils formed in rhyolitic parent material near Mercury, Nevada. The rate of accumulation of CaCO 3 (3–5 g m −2 yr −1 ) at Kyle Canyon is an order of magnitude faster than that near Mercury, but is comparable to rates calculated for soils in southern New Mexico and Utah.

Nevada↗
USGS1989

A comparison of soil climate and biological activity along an elevation gradient in the eastern Mojave Desert

Soil temperature, moisture, and CO2 were monitored at four sites along an elevation transect in the eastern Mojave Desert from January to October, 1987. Climate appeared to be the major factor controlling CO2 partial pressures, primarily through its influence of rates of biological reactions, vegetation densities, and organic matter production. With increasing elevation, and increasing actual evapotranspiration, the organic C, plant density, and the CO2 content of the soils increased. Between January and May, soil CO2 concentrations at a given site were closely related to variations in soil temperature. In July and October, temperatures had little effect on CO2, presumably due to low soil moisture levels. Up to 75% of litter placed in the field in March was lost by October whereas, for the 3 lower elevations, less than 10% of the litter placed in the field in April was lost through decomposition processes. ?? 1989 Springer-Verlag.

Oecologia↗