Sea levels in the early Holocene were not yet at their present height in this region — the continuing melting of distant ice sheets was still adding water to the oceans, and the complex interplay of sea-level rise and isostatic rebound (the rising of the land as the weight of the ice sheet was removed) created a shoreline history that varied across different parts of the coast.

In some areas, relative sea level was higher than today in the early Holocene; in others, it was lower.

Understanding the specific shoreline of Shuká Káa’s time requires detailed geological analysis of the specific area.

What can be said with confidence is that the man lived on an island in a post-glacial world of extraordinary marine richness, where the specific geography of the Alexander Archipelago — its complex coastline of protected waterways, its abundance of salmon and marine mammals, its productive rocky shorelines — provided a marine resource base capable of supporting mobile, maritime-adapted people in comfort and in numbers.

Life on the Water: The Maritime People of the Early Coast