Cryptotephrochronology was used in Alaska to find hidden volcanic ash layers in sediments. The study found a new tephra from Mt. Churchill called the 'Lena tephra' and identified a mid-Holocene tephra likely from an Aniakchak eruption. Other tephras were linked to White River, Mt. Churchill, Redoubt, and Augustine volcanoes. This shows Mt. Churchill has been more active in the Holocene than previously thought, which could impact volcanic hazard assessments in the region.