Lichenometry of the Juneau Icefield

Emily Baker, Class of 2002

Department of Geology, Whitman College, Walla Walla, WA

            Lichenometry has been used for dating moraines before on the Juneau Icefield, but it has been done on the coastal side of the icefield.  The dating has been done with Rhizocarpen geographicum in those areas.  The summer of 2000 lichenometric dating was used on the ëLittle Ice Ageí lateral moraine of the inland Llewellyn Glacier.  The techniques for this dating were revised from past due to further research in the subject of lichenometry.  A new growth rate was determined by going to the graveyard in the closest inland town. This was done because the climate inland is so different from the coastal climate that the growth rate for the coastal was assumed to not apply to the R. geographicum on the inland side of the icefield.  After calculating the data the growth rate for the lichen was 1.5 cm for a 100 years.  Using this growth rate the age of the Llewellyn moraine is at minimum 135 years old.