Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6446375 | Quaternary Science Reviews | 2014 | 12 Pages |
Abstract
Past extents of Bregne ice cap are marked by moraines and registered by sediments in downvalley lakes. 10Be ages of bedrock and boulders outboard of the moraines indicate that Bregne ice cap was within â¼250 m of its present-day limit by at least 10.7 ka. Multi-proxy data from sediments in Two Move lake, located downvalley from Bregne ice cap, indicate that the ice cap likely completely disappeared during early and middle Holocene time. Increasing magnetic susceptibility and percent clastic material from â¼6.5 to â¼1.9 cal ka BP in Two Move lake sediments suggest progressively colder conditions and increased snow accumulation on the highlands west of the lake. Laminated silt deposited at â¼2.6 cal ka BP and â¼1.9 cal ka BP to present registers the onset and persistence of Bregne ice cap during the late Holocene. 10Be ages of boulders on an unweathered, unvegetated moraine in the Bregne ice cap forefield range from 0.74 to 9.60 ka. The youngest 10Be age (0.74 ka) likely represents the age of the moraine whereas older ages may be due to 10Be inherited from prior periods of exposure. This late Holocene moraine marks the second largest advance of the ice cap since deglaciation of the region at the end of the last ice age. The oldest moraine in the forefield dates to â¤2.6 cal ka BP. The fluctuations of Bregne ice cap were likely influenced by Northern Hemisphere summer insolation throughout the Holocene and abrupt late Holocene cold events.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Laura B. Levy, Meredith A. Kelly, Thomas V. Lowell, Brenda L. Hall, Laura A. Hempel, William M. Honsaker, Amanda R. Lusas, Jennifer A. Howley, Yarrow L. Axford,