Archeological sites are test excavated to assess their significance to the National Register of Historic Places. These excavations have contributed new and unanticipated information about indigenous use of the mountains, including the use of alpine obsidian sources in NOCA for the last 5,000 years; the establishment of regular travel routes for the movement of resources and people; the exploitation of mountain goats and other native fauna and flora; a geologic record of Cascade volcano eruptions which are used to mark the timing of both human and climatic events; and a radiocarbon chronology providing a timescale for human uses, natural events, and climatic changes in the North Cascades. Recent research at Cascade Pass has yielded a wealth of data about human activity spanning the last 9,600 years.