Comment on “Record of MIS 5 sea-level highstands based on U/Th dated coral terraces of Haiti” by Dumas et al. [Quaternary International 2006 106–118]

The opening sentence of the introduction [Dumas, B., Hoang, C.-T., Raffy, J., 2006. Record of MIS 5 sea-level highstands based on dated coral terraces of Haiti. Quaternary International 145–146, 106–118] “Quaternary sea-level changes are mainly deduced from the study of raised coral terraces” involves a flawed premise. As two undefined variables operate simultaneously (sea-level changes and vertical tectonic motion; both perhaps having up and down components) to produce a succession of terraces, it is impossible to solve the equation without supplying real numbers for either variable. Hence, to deduce sea-level history, either largely unprovable assumption about constant uplift and/or featureless sea-level histories are required, or a model of sea level must be imported from regions that have not experienced tectonic displacement. Furthermore, coral reefs are less than ideal monitors of sea-level change; rather, they might be preferred as monitors of sea level stability, as their response time and depositional tempo may be measured in hundreds or thousands of years. Reefs may grow and flourish during slow rise of sea level. Once accommodation space is filled, vertical growth ceases, and only erosion and diagenesis of the reef occurs, until sea level changes once more. Major intervals of sea-level change may thus be lost or never recorded in the rocks.