Glacier advance and retreat in Glacier Bay National Park and Preserve has a complex history throughout the Holocene. Evidence from dendrochronological and radiocarbon analysis indicates that there was ice at the mouth of Wachusett Inlet at least 400 years before the tidewater glacier advanced from the head of the inlet to the mouth. This supports the hypothesis that the area was locally glaciated by Burroughs Glacier before the tidewater glacier advanced down the entirety of Wachusett Inlet. Previous work done in Muir Inlet shows evidence that as ice advanced across the West Arm and into Muir Inlet, it dammed Lake Muir. The dates from previous studies show the damming of Muir Inlet to form Glacial Lake Muir around 550 BCE. A radiocarbon date from Stump Bluffs at a mid fjord location in Muir Inlet places ice there between 1-220 CE. This interval of ice advance suggests that as Glacial Lake Muir was filling, ice was simultaneously advancing into it from the north.
This study also added tree ring data to an Adams Inlet chronology, expanding it by 59 years to span from 161 CE to 640 CE. The earlier date of 161 CE constrains when Glacial Lake Muir had to be drained to allow forest growth in Adams. The kill event in the early 600’s CE is hypothesized to be caused by inundation by Glacial Lake Adams formed by Muir Glacier damming the inlet. The Stump Bluffs date of 1-220 CE and the date of 640 CE on Glacial Lake Adams suggests that Muir Glacier advanced ~20 km in less than 600 years.
Downes, Zachery, "Dating the Glacial History Near Wolf Point, Muir Inlet, Glacier Bay National Park and Preserve, Southeast Alaska" (2015). Senior Independent Study Theses. Paper 6645.
Geology | Glaciology
Bachelor of Arts
Senior Independent Study Thesis
© Copyright 2015 Zachery Downes