Rock type and dust influx control accretionary soil development on hillslopes in the Sandia Mountains, New Mexico, USA

Lower slopes of the Sandia Mountains are characterized by granitic corestone topography and weathering-limited slopes with thin grusy colluvium and weakly developed soils. In contrast, thick soils with illuvial clay and pedogenic carbonate have developed below aplite outcrops. Aplite is resistant to chemical decomposition, but physically weathers to blocky clasts that enhance surface roughness and erosional resistance of colluvium, promoting accumulation of eolian fines. Thick B horizons on aplite slopes indicate limited erosion and prolonged periods of stability and soil development. Accretion of eolian material limits runoff and prevents attainment of a steady-state balance between soil production and downslope transport.

Paleoclimatic implications of middle Wisconsinan pollen and a paleosol from the Purcell Trench, south central British Columbia

A paleosol and organic-rich horizons occur in Bessette Sediments near Meadow Creek, south central British Columbia. The paleosol is at least 42 000 years old and formed on a paleoslope adjacent to some precursor to Meadow Creek. On higher parts of the paleoslope, the soil developed under locally dry conditions and influxes of eolian material; a regosol formed near the base of the paleoslope marginal to a floodplain. Pollen assemblages from the organic-rich horizons are grouped into two assemblage zones. MC 1, approximately 42 000 years old, is dominated by arboreal pollen, mainly Picea. MC 2 (approximately 34 000 years old) is dominated by Picea in conjunction with significant amounts of Tsuga heterophylla. Paleoclimatic implications of the assemblages are that temperatures 42 000 years ago were approximately 3 °C cooler than present but by 34 000 years ago had ameliorated and were similar to or slightly cooler than present.

THE DESCRIPTION, CHRONOLOGY AND CORRELATION OF BURIED SOILS AND CULTURAL LAYERS IN A TERRACE SECTION, PEACE RIVER VALLEY, BRITISH COLUMBIA

A terrace section in the Peace River Valley of British Columbia contained seven buried paleosols developed in eolian material. Chemical, physical and micromorpholgical data showed the soils to be Chernozemic. The main soil-forming processes have been the leaching and reprecipitation of carbonates, the formation of mull aggregates, the weathering of primary minerals and the weak physical translocation of soil fabric. Five cultural components or levels had been identified in nearby archaeological excavations and these were correlated with the Ah horizons of five of the paleosols. However, none of these Ah horizons contained large amounts of organic P as have been found in cultural layers of other archaeological sections. The cultural components contained tools, flakes, shell beads, bones and projectile points. Radiocarbon dates from charcoal ranged from 5830 ± 80 yr B.P. in the second lowest paleosol to 1530 ± 70 yr B.P. in the second highest paleosol. They showed that most of the eolian material had been deposited on the terrace by about 4500 yr B.P.; that is, by the end of the Hypsithermal. The chronology of soil development and eolian deposition are discussed by applying a previously published system of horizon designations that combines and describes the gradational and pedomorphic features in soils.

Existence d'un desert froid au Quaternaire ancien dans la region littorale vendeenne

The early Quaternary history of the coastal region of Vendee, France, is reconstructed from study of eolian sands veneering the upper sides of valleys. At the time of the first glacial stage, the region was covered by thick desert sands. That this cold desert was not entirely devoid of vegetation is indicated by fossil soils in the quarries at Pin and Roussiere. Subsequently, most of the eolian material has been reworked into terraces by streams and by the sea.