Historical sea level and accommodation zones along Baja California

Senior thesis written for Oceanography 444[Author's Abstract] Change in sea level is an ongoing process which alters the coastal ecosystem on a continuous basis. The physical changes in the world’s coastal ecosystem due to sea level change have occurred many times over the course of Earth’s history. While there are a number of large scale processes which contribute to localized variation in the sea level, such as land subsidence changes in the rate of sedimentation from local rivers, and alteration in coastal circulation patterns, climate change remains the dominant process and control of sea level. Climate and sea level variability have left behind evidence in the structural formation of the seafloor that can be seen today in the form of a step-like pattern on the continental shelf. A high resolution multibeam sonar survey was used to gather evidence of historic sea level change from the sea floor along 4 transects of the Baja California peninsula and mainland Mexico continental shelf. Variation in the structural pattern along these transects is used to identify potential historical shorelines. Step-like structures were found at three locations at the lowest point of sea level, indicating a change in a global process for historic sea level, and intermediate step-like patterns are evident that a variety of distance along the transect until the present day shoreline. This research provides insight into the spatial variability of sea level rise and contributes to our understanding of the complexity associated with local scale planning for sea level rise