Tlingit Legends and Tree Ring Dated Little Ice Age Maximum in Glacier Bay during the Early 18th Century

Geological, geophysical and ethnographic studies in Glacier Bay are consistent with catastrophic rates of ice expansion into Tlingit communities and concomitant relative sea rise on the order of three meters as subsidence under ice loading. The timing of these changes dated to the late 1600s has been based on radiocarbon dating of submerged and now emerging forests buried by the ice or by inundations with subsidence. We report here on new tree-ring, calendar dates from the outer rings of logs recovered from the intertidal zones of the southern reaches of the Glacier Bay fiord complex. The ongoing tree-ring dating shows that ice expanded across the lower bay from 1704AD to 1735AD.

The death of the forests may be due to multiple causes, including overriding by ice, proglacial sedimentation and possibly crustal deformation by ice loading. Our data indicate trees were killed along a 5 km flow line within a few decades, which suggests rapid ice expansion rates of about 2 km per decade. Such a rapid rate of advance is consistent with Tlingit legend of an ice advance forcing them to flee their village believed to be located near the 1704 margin in the Bartlett Cove area.

In addition, Tlingit legends report two years of continuous winter conditions about the time of the Tlingit-evicting LIA ice advance. Interestingly, our tree-ring records show extreme cold between 1752 and 1754, possibly reflecting this event. Cooling during these years is not seen in other coastal Alaska series and thus may be a local effect amplified by the expanding Glacier Bay Icefield.