Driven young geologist Ernest deKoven Leffingwell--with assistance from his Inupiat neighbors--completed groundbreaking work on the Arctic frontier. Eager to investigate rumors of land north of Alaska, Leffingwell and fellow 1901 Baldwin-Ziegler Expedition explorer, Ejnar Mikkelsen, organized the 1906 Anglo American Polar Expedition. Although pushed to their limits, the men determined the edge of the continental shelf--a significant geographic discovery. Leffingwell stayed behind, and between 1906 and 1914, pioneered research in ground ice (permafrost), surveyed and documented the geography of the coastline and interior, studied birds, and collected wildlife specimens for the Smithsonian Institution.