Desert pavements with stratified soils as indicators of Quaternary landscape development

Desert pavements are peculiar features of arid environments. Models describing pavement evolution involve removal of fines, upward migration of stones and dust accumulation. However, morphodynamic influence of relief often remains poorly represented. Stratified soils are common in environments affected by changing climate regimes. They integrate signals of landscape evolution. Stone layers, composite or buried soil horizons, and grain-size breaks indicate different stratae, each representing distinct geomorphodynamics.

We present preliminary results from field campaigns in North America. From Cima Volcanic Field, Mojave Desert, California, we describe a soil profile on a 560 ± 80 ka old lava flow, showing above mentioned features of stratification, and present accompanying OSL ages.

From Black Rock Desert, southern Sevier Basin, Utah, we show vesicular horizons and desert pavements at their apparent current climatic range limit. The moisture gradient within the semidesert basin allows us to study the influence of humidity on the evolution of desert pavements.

Laguna Salada, Baja California, Mexico, holds very young soils on abandoned alluvial fan surfaces. Regardless of surface age the vesicular horizon depth reaches 3 to 4 cm. Although buried vesicular horizons occur, compound deeper horizons are missing. On an approx. 20 year old, artificial surface a desert pavement begins to develop with 1 cm vesicular horizon underneath.

Soils beneath desert pavements on Lanzarote, Canary Islands, reveal preserved vesicular features in strongly developed, clay enriched horizons.

From these study areas we conclude that desert pavement development is a sometimes rapid but nonlinear combination of geomorphic processes strongly depending on climatic presetting. The tight relationship of pavement and vesicular horizon properties, in combination with micro relief suggest complex evolution models to explain the observed phenomena. Compound horizons together with layering represent the impact of climate and thus, landscape change. They can be used to disentangle the complex history of specific sites.