Lichenometric dating of holocene moraines at Mount Edith Cavell, Jasper, Alberta

Abstract

A preliminary growth curve for the lichen Rhizocarpon geographicum over a 250 yr period was determined on moraines of quartzite debris at Mount Edith Cavell and Penstock Creek, Jasper National Park, Alberta. The dating control was obtained by dendrochronology and from documentary and photographic sources. The average growth over this period is 25 mm/century but the curve appears to be exponential in form and can be subdivided into 42 mm/century for the first 110 yrs and 11.4 mm/century for the subsequent 140 yr. The latter figure gives a maximum estimate for the linear phase of R. geographicum in this area. Four Little Ice Age moraines are identified and dated as 1705 .+-. 5, 1720 .+-. 5, 1858 .+-. 7 and 1888 .+-. 7 A.D. at Mount Edith Cavell, and 1765 .+-. 5, 1810 .+-. 5, 1876 .+-. 5, and 1907 .+-. 5 A.D. at Penstock Creek. Recession of Cavell Glacier averaged about 16 m/yr from 1927-1963 and 6-8 m/yr from 1963-1975. Angel Glacier shows a similar pattern but has maintained its frontal position since 1962. Remnants of at least 3 pre-Little Ice Age, moraines occur in 2 small areas at Mount Edith Cavell. The minimum lichenometric age for the oldest moraine is about 1800 B.P. The presence of Bridge River Ash in the soils in front of the 1705 moraine indicates no greater glacial advance in the last 2600 yr. Thus although several glacial advances occurred at this site during the Holocene they were of similar or smaller extent than the Little Ice Age maximum.