GSA QUATERNARY GEOLOGY AND GEOMORPHOLOGY DIVISION FAROUK EL-BAZ AWARD FOR DESERT RESEARCH: A GLOBAL PERSPECTIVE ON THE IMPORTANCE OF DESERT DUST TO SOIL GENESIS IN THE QUATERNARY

Soils play a fascinating role in the global dust budget. In the Sahara and Sahel regions of Africa and in the deserts of Asia, soils are the sources of dust that is transported to nearby and distant locations. Elsewhere, soils are the recipients of dust that has been transported from desert sources, on scales ranging from a few meters to thousands of kilometers. In the deserts of southwestern North America, clay and carbonate particles of eolian origin explain the formation of many Bt and Bk horizons. Eolian transport of clay from the deserts of North Africa is the source of distinctive red Bt horizons in many soils across the northern margins of the Mediterranean region. On an even broader intercontinental scale, transport of dust from Asian deserts has been a factor in soil genesis on many Pacific Ocean islands (including Hawaii), thousands of kilometers to the east. In a similar fashion, transport of African dust from the Sahara and Sahel regions of Africa adds parent material to soils on the continents and islands of the Americas, on the western margin of the Atlantic Ocean. Soil genesis in some recipient regions is inhibited without such eolian additions. For example, soil development on relatively pure carbonate substrates of the northern margins of the Mediterranean would be less dramatic without the additions of fine-grained dust from desert regions of North Africa. Soils of humid tropical regions in the eastern part of the Americas would be much less fertile without the additions of Sahara and Sahel dust. Stratigraphic studies show that addition of desert dust to soils has been an important process through much or all of the Quaternary. For example, studies of paleosols in thick stratigraphic sections show that African desert dust transport across the Mediterranean and Atlantic has been important over many interglacial-glacial cycles. Soil chronosequence studies on both Atlantic and Pacific islands show that additions of dust from Africa and Asia, respectively, have been a part of soil genesis for hundreds of thousands of years. Assessments of global dust budgets need to include desert dust additions to soils, which are significant.