Published online by Cambridge University Press: 20 January 2017
In a dissected, mostly sandy terrain along the Rio Grande valley border of southern New Mexico, a reddish-brown coarse-loamy Haplargid in an eolian deposit has a stage II carbonate horizon that is typical of soils of the Leasburg surface (8000-15,000 yr B.P.). The eolian deposit buries sediments and soils of late Pleistocene age or older. Thus, it does not fit in the chronological framework of the stepped sequence of geomorphic surfaces along the valley border, in which age of the surfaces and their soils increases with increasing elevation of the steps. Because the eolian deposit occurs in isolated areas where its age relative to the stepped sequence cannot be demonstrated geomorphically, soil characteristics are major tools for placing the deposit and its soil in the chronological scheme for the area. On the basis of the stage II carbonate horizon, the eolian deposit is considered to be an eolian analog of Leasburg alluvium. One of the Leasburg Haplargids in eolian sediments on a ridge crest has a total of 23 kg/m2 of pedogenic carbonate. Downslope in an area that receives runoff from higher areas, a fine-loamy Haplargid in Leasburg alluvium has 186 kg/m2 of carbonate; a nearby coarse-loamy Haplargid that does not receive runoff has only 46 kg/m2 of carbonate. Thus, landscape position and texture have a major influence on the total amount of pedogenic carbonate, which can range to more than eightfold in soils of Leasburg age.