As the saying goes: ”What happens in Vegas stays in Vegas”. Well, turns out the ocean is not as good at keeping a secret. Most of what happens in the ocean ends up on the seafloor. As such, sediments are the long-term memory of the ocean, a window into what Earth looked like thousands or even millions of years back in time. From this muddy library we can learn about the rise and fall of the sea as polar ice sheets have come and gone. There were no thermometers when the dinosaurs roamed the Earth, but marine sediments can tell us that the planet was very much warmer 65 million years ago… that is, until that huge meteorite hit the Earth, causing the end of an era, and turning the Earth into an (nearly) unihabitable wasteland for the next few decades. And guess what, traces of that meteorite impact can be found in the thick sediment layers just off the New Jersey coast. In the deepest part of the ocean where there is no sediment cover, seawater is sucked into the seafloor along huge mountain ranges. As the seawater is heated in the crust, it extracts precious metals from the Earth, and where the hot seawater re-emerges it gives life to some of the most intriguing life forms that populate hydrothermal vents. Maybe it is the seafloor near such hydrothermal vents that holds the secret to how life on Earth began. And ironically, some ancient seafloor from the earliest part of Earth’s history can now be found in the desert of Nevada, just outside Vegas.
Reconstructions of former sea levels provide context to frame recent accelerations and refine future projections of sea-level rise. Sea-level reconstructions help refine model predictions of glacial-isostatic adjustment (GIA) and aid our understanding of the spatial and temporal response to climate change. Sea-level reconstructions from coastal sediments are relevant to varied disciplines including studies of coastal evolution and wetland development, ice-sheet history, paleoclimate and understanding the environmental context of human activity. Reconstruction from coastal sedimentary record also provide an archive of the occurrence of former earthquakes, tsunamis and tropical cyclones. Observational and instrumental records are too short (particularly for less frequent, high magnitude events) to provide a reliable basis for predicting future activity Therefore, coastal sedimentary records are a valuable tool to assess future risk.