Research conducted by the Presidential Young Investigator will focus on development and application of methods for reconstructing environmental changes, using terrestrial records having both time control and wide distribution. New dating and paleoen vironmental methods developed by the Principal Investigator for rock varnish coatings, will permit radiometric age assignments and chronometric age-determinations of many previously undateable desert surfaces. Chemical changes in surface coatings have been found to record systematic variations in past levels of dust, alkalinity and photosynthetic pathways of adjacent vegetation. The next phase of research includes study of hillslope debris in humid-temperate environments and further development of rock varnish dating methods. Understanding environmental changes depends on obtaining "proxy" records that are both dateable and ubiquitous. Desert varnish and slope colluvium deposits hold great promise to provide important information for paleoenviromental reconstruction of past events in both semi-arid and humid environments.
