Having a large tidal range; J. L. Davies (1980) defines microtidal as having a range less than 2 m, mesotidal 2–4 m, and macrotidal over 4 m. Areas with a tidal range over 10 m are sometimes distinguished as hypertidal (Allen (2000) Quat. Sci. Revs 19). Macrotidal estuaries have their dynamics dominated by tidal forcing, as compared to the forcing imposed by the river (Regnier and Steefel (1999) Geol. & Cosm. Acta 63, 9). Reichmüth and Anthony (2007) Geomorph. 90, 3–4 explore the relationship between tidal influence and intertidal bar–trough systems in a macrotidal setting. Macrotidal sandy beaches are thought to represent optimal conditions for coastal dune development (Ruz and Meur-Ferec (2004) Geomorph. 60, 1–2).