Identification and quantification of weathering by plant roots

Small weathering forms were produced on polished marble tablets by the etching action of plant roots. Imagery of the forms was obtained with a high quality photogrammetric scanner. Automated classification methods, used in image processing, proved inadequate for identifying etched areas, but observer defined mapping within a GIS was able to identify and map the extent and intensity of etching across a range of scales. Root etching patterns were not apparently influenced by forms produced during tablet preparation. Root etching occurs across grains and at grain boundaries, and appears to be more intense at the junction of root networks.