Calcic soils of the southwestern United States

Stable isotopes of pedogenic carbonates as indicators of paleoecology in the Plio-Pleistocene (upper Bed I), western margin of the Olduvai Basin, Tanzania

“…The depth of precipitation varies for each soil, and is controlled by soil moisture and texture (Gile et al, 1966;Machette, 1985). Carbonate supersaturation due to soil drying during évapotranspiration is generally considered the primary mechanism for CaCOs precipitation (e.g., Jenny, 1980;Cerling, 1984;Quade et al, 1989b), which typically occurs in well-drained soils in the vadose or unsaturated zone above the influence of the groundwater table (Fig.…”

Sand sheet dynamics and Quaternary landscape evolution of the Selima Sand Sheet, southern Egypt

“…In the large buried channels revealed by SIR-A radar images ) the alluvial deposits are light gray (10YR) to light brownish gray (7.5YR) to white where strongly cemented by calcium carbonate (stages I11 and IV of Machette, 1985). On the low uplands away from the buried SIR-A channels or depressions, alluvial deposits show varying degrees of induration from firm, friable to hard with colors ranging from browns (7.5YR) to reddish brown (5 YR) to red (2.5YR) and stages of calcification ranging from stage I1 to stage 111.…”

Impacts of interrelated biotic and abiotic processes during the past 125000 years of landscape evolution in the Northern Mojave Desert, Nevada, USA

“…Shrub undercanopy and intercanopy profiles were described at each site. Soil samples from each horizon were analyzed at the Desert Research Institute's Soil Characterization and Quaternary Pedology Laboratory for particle-size distribution using laser light scattering (Gee and Or, 2002), carbonate content using Chittick apparatus (Dreimanis, 1962;Machette, 1985), and electrical conductivity (Rhoades, 1996). Particle-size distribution of the less-than-2-mm fraction was determined as a volume percent of each major fraction (sand, silt, and clay).…”