Magneto-Susceptibility Event and Cyclostratigraphy (MSEC) is used here as a means of establishing sensitive chronostratigraphic markers and chronohorizons useful for high-resolution correlation. MSEC is a composite of the magnetic susceptibility (MS) record of marine strata and the coeval biostratigraphic record and, similar to chronozones, zones based on MSEC data have boundaries that are isochronous. MS, a measure of the concentration of magnetic grains in sediments, proxies for the ratio of lithogenic to biogenic components. Controls on the detrital input of lithogenic material include eustasy and climate, however induced, and sea floor/basin subsidence. The development of an initial MSEC composite reference curve for the Middle-Upper Devonian of the Anti-Atlas region of southern Morocco is presented and discussed in the context of global sea level transgressive and regressive cycles. MSEC trends, composed of increasing MS magnitudes, correlate well with episodes of regression, whereas trends of decreasing MS magnitudes correlate with episodes of transgression.