We determine the location of the peat sample within the intertidal framework using benthic foraminifera, and we know the distance of the sample below the marsh surface. We thus can determine for each sample in the core where it was located with regard to mean sea level or th level of mean high water, and we can observe this also for the marsh surface. We then can derive how the environment changed at the core location: from high to low marsh, for instance. We can then date the samples, and derive a mean high water rise curve from the marsh paleoenvironment curve. See the Poster on Dennis Creek or the Poster on the Connecticut and Housatonic marshes for an example.