Chapter 2 Late holocene sea level variation

Abstract

This chapter describes how the U.S. Atlantic Coast is used to trace the history of sea-level rise during the late Holocene, focusing on the record of the past several thousand years as an example of the relations between climate and sea level. Historically, geomorphic features have provided the clearest evidence of a former change in sea level. Erosion and inundation during transgressions, or prolonged periods of rising sea level, often erase or submerge former sea-level positions. Biological indicators, such as shells or tree stumps, for reconstructing former sea levels can be very persuasive evidence of significant sea-level changes. This is the case especially where fossils of upland tree species are recovered from considerable depth of water in continental shelves or where fossils of deepwater fauna crop out in sediments occurring substantially above modern sea level. The example of Charles Darwin clambering among rocks high in the Andes during the voyage of the Beagle and the inescapable conclusions he reached regarding crustal uplift upon encountering fossils of rugose corals is significant in this context. Similarly, fossils of mammoths and mastodons found in surficial sediments of the inner shelf of the U.S. East Coast testify to the depth of the regression during the last glacial maximum.