“…They are found worldwide under a variety of climate, hydrodynamic and sedimentologic conditions. Some of the well-documented examples include the east coast of China (Ren, 1986;Wang and Wall, 2010), the Severn Estuary of the UK (Williams et al, 2008;Carling et al, 2009), the Amazon Estuary of South America and Fly River mouth of Oceania (Allison et al, 1995;Walsh and Nittrouer, 2004), the northwest coast of America (Fagherazzi and Mariotti, 2012;Nowacki and Ogston, 2013), and the west coast of the Netherlands (Kleinhans et al, 2009). …”