UC San Diego

Archaeological sites related to the first humans on North America's Pacific Coast may be preserved offshore, but finding those sites remains a challenge. Rising sea levels threaten to destroy near-shore sites, adding urgency to the question of how to find and preserve vulnerable cultural heritage resources. Current best-practices include reconstructing drowned landscapes as they were during possible human occupation. In chapter 3, we investigate the submerged San Dieguito river valley. Humans were nearby, on the Northern Channel Islands, by the time of the Younger Dryas, a thousand-year period of stable sea level and relatively cool temperatures. We use sub-bottom sonar and sediment cores to map the offshore extent of the river valley, and to gain insight into the local landscape during the Younger Dryas period. While our interpretations can be used to make predictions about human landscape use, it would be better to locate verifiable archaeological material. Chapter 1 lays some needed foundation for developing a reliable method to detect lithic (stone) artifacts during sub-bottom sonar surveys using their resonance properties. This method could augment surveys, like that of chapter 3, to include potential artifact deposits in the mapped landscapes. As we make efforts to use sound to preserve human heritage, we acknowledge that marine mammals have been using sound in the ocean for much longer. The noise humans add to the underwater soundscape could interfere with their daily activities. In chapter 2, we study the hearing mechanisms of whales, and use methods adapted from those in chapter 1 to measure the resonance properties of fin whale ear bones. Understanding how marine mammals hear can help us mitigate negative impacts from our methods, and learning how they use sound could even help us design more effective sonar instruments. In the three chapters combined, we study the ringing tones of stones, bones, and coastal zones to tune the protection of marine mammals and cultural heritage.