Little Ice Age fluctuations of small glaciers in the Monte Fitz Roy and Lago del Desierto areas, south Patagonian Andes, Argentina
Abstract Current knowledge about late Holocene glacier fluctuations in the south Patagonian Andes is mainly based on evidence from large outlet glaciers of the North and South Patagonian Icefields, and few data exist for the smaller glaciers elsewhere in the region. Here we provide dendrogeomorphological evidence for Little Ice Age (LIA) and post-LIA activity for five small glaciers near the northeast margin of the South Patagonian Icefield. The study sites include Glaciar Torre and Piedras Blancas in the Monte Fitz Roy area, and three adjacent glaciers near Lago del Desierto. At these sites the LIA maximum position was identified by massive moraines with mature trees dating to the late 1500s–early 1600s. Several older moraines were observed beyond these limits but could not be precisely dated. Relatively synchronous advances occurred at most glaciers in the early 1700s and were dated using living trees and in situ , subfossil material. All glaciers show three to five subsequent advances mostly concentrated between the mid-19th and early 20th centuries. Estimates based on Landsat TM imagery indicate these glaciers lost between 15 and 46% of their LIA areas by 1984 and a further 5–18% by 2005, with the smallest glaciers showing the greatest proportional loss. Paired comparisons of contemporary and the earliest known photography for the glaciers in the Fitz Roy area confirm this mass loss. These results provide important new information on the glacier history of this area but additional, more precisely-dated records are needed from many more sites before we can fully elucidate the complex late Holocene glacial history of this region.