Different proposals on how to define a hierarchy sys tem (e.g.,
Vail et al., 1977, 1991; Mitchum and Van Wagoner, 1991; Embry,
1995; Krapez, 1996, 1997) have stimulated active discussions
within the stratigraphic community (e.g., Miall, 1995, 1997;
Drummond and Wilkinson, 1996; Schlager, 2004; see recent
summaries in Catuneanu et al., 2009, 2010).