Glaciers play a prominent role in climatic research, since they are important monitoring agents and their fluctuations carry information on past climates. Dendroglaciology allows dendrochronological techniques to be applied to the reconstruction of glacier fluctuations (Schweingruber 1988, 1996, Luckman 1995). In Southeast Alaska, glaciers extended into forested areas enabling dendrochronological techniques to be applied to the reconstruction of glacial dynamics in two ways: (1) Advancing glaciers in the past tilted and overran trees whose remnants, sub-fossil wood, allow former glacial advances to be dated. (2) Retreating glaciers leave bare areas that are rapidly reforested due to the favorable climate. Tree rings provide a precise date for advance or, in this case, for retreat when terminal moraines became ice-free.
The Eagle, Herbert and Mendenhall Glaciers are all part of the Juneau Icefield located in the Juneau area, Southeast Alaska (Fig. 1). In a previous study, Lacher (1999) found that the forefields of the Herbert and Mendenhall Glaciers have several well-developed, densely vegetated terminal moraines dating back to the Little Ice Age ca. 1750 to 1960 AD. He collected subfossil wood and built floating chronologies, but these chronologies could not be linked to recent chronologies and thus they could not be calendar dated. To continue this work, we sampled living trees from different stands near the Eagle Glacier and also subfossil snags in the forefields of all three glaciers. Furthermore, in situ stumps that were rooted in a lower soil level were collected in the riverbeds of the Mendenhall and Herbert Rivers. Our objectives are: (1) to reconstruct fluctuations of Eagle glacier, (2) to establish continuous tree-ring chronologies for the last millennium and (3) finally to gain insight into the climatic history of the region. Here, we report the dating of glacial stands in the forefield of Eagle Glacier.