Late-Holocene glaciation and twentieth- century retreat, northeastern Brooks Range, Alaska

Abstract

Lichenometric dating of moraines deposited by eight glaciers in the northeastern Brooks Range suggests major glacial advances or stillstands at about 2600, 1000, 450, and 60 lichenometric (L) years BP. The latter two advances of the early-middle and latest part of the 'Little Ice Age', respectively, formed promi nent moraines at all glaciers studied. In response to overall twentieth-century warming, these glaciers have retreated at average rates of 2 to 19 m yr^-1 from the distinct ridges formed in AD 1890. Glacier thinning at rates of 0.7 to 0.9 m yr^-1 accounts for over 90% of the ice loss.