Abstract

The glaciers of Alaska have undergone intervals of advance and retreat throughout the Holocene. Over the last 4000 years, the tidewater glacier in Glacier Bay has undergone multiple alternating periods of advance and retreat. Tree-ring analysis and radiocarbon ages from overrun forests provide evidence of these advances. The oldest dated sample in this study pointed to a possible advance at approximately 4150 BP. Another period of advance, centered on 3000 BP, was constrained by a study in 2007. During the first millennium AD, an advance was determined by the tree-ring dating of overridden logs and may be related to a contemporaneous advance documented in a previous study. Tree-ring dating and the presence of outer rings gave evidence that this advance was occurring by AD 650. Another period of advance is known to have taken place in Glacier Bay during the Little Ice Age. Two samples from this study have been radiocarbon dated to the Little Ice Age advance, but they cannot provide more detail on this advance without tree-ring dating. The kill dates of AD 650 and roughly AD 1700 are consistent with previous reconstructions of past ice movement within Glacier Bay and other Alaskan glaciers. The first millennium AD and Little Ice Age kill dates have helped to fill gaps in the glacial history of Glacier Bay, in some cases with decadal precision. Since the Glacier Bay glacier was a tidewater glacier, it may not have always responded to changes in climate. Nonetheless, it is of substantial importance that we understood more about the glacial history and behavior of Glacier Bay and other Alaskan tidewater glaciers.

Advisor

Wiles, Gregory C.

Department

Geology

Disciplines

Glaciology

Publication Date

2009

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2009 Michael Krivicich