Glacier and Vegetation Dynamics on Mt. Baker, WA Since the Little Ice Age

Keywords: glacier, climate change, biogeography, Pacific Northwest
Abstract Type: Paper Abstract

Abstract

The Easton Glacier on the southside of Mt. Baker, Washington has been the focus of many studies examining glacier mass balance, glacier recession, and the resulting primary ecological succession on its foreland. Several of these studies have noted a gap in the literature regarding glacier’s terminus position prior to the air photo record (<1940), including the Little Ice Age (LIA) deposits which are clearly identified in nearby valleys. This study has refined the glacier’s terminus position by using dendrochronological methods, specifically using tree establishment to date surfaces exposed by glacier retreat since the LIA. A chronology of the Easton glacier’s terminus position over time was created showing its recession and advancement since the late-LIA. The Easton glacier retreated a total of 2,653 meters 1880-1956, advanced 574 meters between 1956 and 1990, followed by the on-going retreat. The Easton Glacier’s LIA moraines were located in an adjacent valley, indicating that the melt-stream has undergone an avulsion, leaving the LIA deposits high and dry compared to the modern stream location. This study also determined ecesis, the time interval between deglaciation and vegetation establishment: ~8 years at the bottom of the foreland (~1200 m elevation) and ~28 years at the top of the foreland (~1700 m). This trend of longer ecesis intervals at higher elevations reflects the colder conditions and further distance from seed sources compared to lower elevations. The findings from this study can be used to inform on the Easton glacier’s response to climate change and other environmental factors.