Cosmic ray labeling of erosion surfaces II: Special cases of exposure histories of boulders, soils and beach terraces

The recent realization that cosmic ray induced isotopic changes in terrestrial solids can be conveniently measured, and the information applied towards modeling their exposure histories has been very successfully put into practice for quantitative studies of a number of process studies in geomorphology. However, in some cases, it is not possible to make a robust interpretation of the cosmogenic data in cases where one does not have sufficient amount of useful geological data about the samples under study. entirely on the fact that cosmic ray labeling is sensitively dependent on the geometry of exposure of the solid, we present new approaches for studying certain important geomorphic processes. The absorption of the secondary cosmic radiation within the solid depends on the secondary cosmic ray component that is principally responsible for causing the in-situ isotopic change. In this paper we will largely be concerned with the fast neutron component of the cosmic radiation which is responsible for most of the isotopic effects in solids exposed at or above sea level. With the four examples considered in this paper, we demonstrate that if one takes advantage of the geometry sensitive labeling by fast neutrons, one can obtain valuable information on the exposure history of the solid, for example determining both the exposure age of a solid as well as the mean surface erosion rate during the exposure. Realization of this possibility should considerably widen the scope of applications of the cosmogenic method in geomorphology.