Catastrophic sealevel rise due to ice-sheet collapse is one of the major worries for coastal communities like S-Florida. Using the past as a key to the present and future, we will use the growth history of S-Florida coral reefs to test whether such catastrophic sealevel (~5-6m in ~100 years) rise did indeed occur in Broward County 8000 years (8ka) ago. Such a hypothesis has been put forward based on Broward shelf geomorphology, but preliminary data could neither verify nor falsify it. We propose to drill submerged coral reefs in Broward County to obtain detailed age-with-depth data to reconstruct sealevel rise and find ultimate clarification whether final instability of the Laurentide icesheet caused catastrophic sealevel rise 8ka ago. Such information is valuable for forecast models, since instability of the Greenland ice-sheet has been implicated with theoretical future catastrophic sealevel rise scenarios. For this project, we leverage infrastructure and equipment built from other grant sources. Collaboration with Manchester Metropolitan University and the University of Kiel will allow access to the latest radiometric dating techniques and will provide training for a PhD candidate at NSU. The project will also pay for the data required for this NSU dissertation, and will provide a visiting student from ETH Zurich with an internship opportunity.