R. Dorn, Arizona State University

F.M. Phillips, New Mexico Tech

Physical Geography, 12 (1991) 303-333

The past decade has seen the development and application of over a dozen new methods for quantitative age-determinations of geomorphic surfaces. Some surface exposure dating methods are numerical, including the accumulation of cosmogenic radionuclides 10Be, 14C, 26Al, 36Cl, and 41Ca, a accumulation of cosmogenic stable nuclides 3He and 21Ne, 14Cl dating of organic matter encapsulated in rock coatings and dendrogemorphology. Calendar ages are obtained by dendrogeomorphological analysis. Calibrated ages can be obtained by analysis of rock-varnish chemistry, lichenometry, weathering, and soils. Various methods can be used in combination to overcome individual limitations. Whereas conventional methods provide age control on stratigraphic profiles, surface-exposure dating methods are especially suitable for geographic problems, such as analyzing not only temporal, but also spatial variations in the rates of geomorphic processes. [Key words: geomorphology, process, geochronology, cosmic nuclides, Quaternary, surface exposure dating, rock varnish, weathering, soils.]