The indicative meaning calculator – quantification of paleo sea-level relationships by using global wave and tide datasets

The study of past sea levels relies largely on the interpretation and quantification of sea-level indicators. These are fossil coastal landforms, bioconstructions or deposits that have a quantifiable relation to paleo sea level (called the indicative meaning) and can be assigned an age of formation. The calculation of the indicative meaning should always rely on the quantitative comparison between the paleo sea-level indicator and the elevational range of the same feature in the modern environment with respect to modern sea level. This may prove difficult to quantify when no site-specific data is available, for example when compiling databases with large geographic scope. In this paper, we provide a method to quantify the indicative meaning of sea-level indicators using simple hydro- and morphodynamic equations with inputs from global wave and tide datasets. We apply and compare our approach exemplary to data published in a relative sea-level database on the Marine Isotope Stage 5e highstand and show how this approach can help in estimating the indicative meaning if no site-specific data on the modern analog is available. For the easier usability of the described approach in this paper, we also present a stand-alone Java-app (IMCalc), which can be used as a calculator of the indicative meaning.