The First Glacial Maximum in North America
Despite marine evidence for at least 50 Pliocene-Pleistocene ice sheet advances, only the most recent one has been accurately reconstructed from terrestrial evidence, because there are few techniques for dating older glacial deposits. Here we show that the cosmic ray–produced nuclides beryllium-10 and aluminum-26 can be used to date tills that overlie paleosols.
Geography, Geology, and Planning
Balco, Greg, Charles W. Rovey, and John OH Stone. "The first glacial maximum in North America." Science 307, no. 5707 (2005): 222-222.