Automatic Grain Sizing of vertical exposures of gravelly deposits

The Grain Size Distribution (GSD) is a key indicator in stratigraphy and morphology; it is a basic tool used by a variety of disciplines: geology, geomorphology, archeology, ecology and engineering. Automatic Grain Sizing (AGS) has been developed to estimate the GSD of surfaces in a rapid and effortless manner. Yet the traditional bulk method, time consuming and laborious, is still in use for the determination of the GSD of coarse-grained sedimentary deposits and of the near-subsurface of landforms, principally river beds. The AGS technique is examined here in its application to the stratigraphic record and to the subsurface. Images processed by AGS and manual samples of coarse-grained deposits in section were compared for evaluation of accuracy and determination of the extent of validation of the AGS technique.