Lichenometry is a geochronological technique that uses the size of lichen colonies to estimate the age of exposed rock surfaces, particularly in glacial and periglacial environments. This method is valuable in studying the timing of glacial retreat, rockfall events, and other geomorphological processes.
Reference: Innes, J. L. (1985). “Lichenometry.” Progress in Physical Geography, 9(2), 187-254.