Final answer:
Archaeologists can determine when people started to settle on the land bridge through core samples from the sea floor. The discovery of 15,000-year-old rafts and canoes along the Pacific coast would provide further evidence for settlement rather than just movement across the land bridge.
Step-by-step explanation:
Archaeologists can determine when people started to settle on the land bridge, as opposed to just moving across it, by examining core samples obtained from the sea floor. By drilling down into the shallow sea floor, archaeologists have found evidence of large mammals and hunting tools in and around the Aleutian Islands, indicating human settlement. However, establishing and cross-checking dates is difficult because most evidence is now submerged. Additionally, the discovery of 15,000-year-old rafts and canoes along the Pacific coast would provide further evidence for early migration in the Americas. This would support the coastal migration theory and suggest that some populations arrived through following the coast of land across the Bering Land Bridge and down the coast of North America, indicating settlement rather than just movement across the land bridge.