The coastlines of 13,000 to 15,000 years ago are now under water — drowned by the sea-level rise that followed the end of the glacial maximum.

Any sites that early coastal migrants built at or near the ancient shoreline are on the continental shelf, covered by ocean.

Without underwater archaeological investigation, that evidence is inaccessible.

This is a critical point for understanding why the Arlington Springs individual is so significant within the Kelp Highway framework.

The bones were found not at the ancient coastline — which is now submerged — but inland, in canyon sediments.

They survived because they were deposited in a geological context that preserved them above the water table.