Formation of beach‐ridge plains: an appreciation of the contribution by Jack L. Davies

Abstract

A robust debate among coastal geomorphologists as to the processes by which beach‐ridge plains around Australia have formed was initiated by a former President of the Institute of Australian Geographers. This review gives special consideration to the work of Jack L. Davies, whose academic contributions to coastal geomorphology in Australia have not always been appropriately acknowledged when explaining how similar plains have evolved elsewhere in the world. Davies recognised that relatively steep storm waves caused erosion (cut) on beaches, whereas less steep long‐period swell waves returned sand (fill). He considered the beach berm to be the nucleus on which a beach ridge formed, which could subsequently develop into a foredune, in contrast to cobble ridges that were deposited during storms. Offshore conditions regulate supply of sand to the shoreline, partly through effects on wave refraction, with higher rates of supply where the nearshore is shallow. It was apparent to Davies that the elevation of successive ridges might, but not necessarily, provide evidence of past changes of sea level, despite adornment by variable amounts of windblown dune sand. Morphodynamic understanding of long‐term coastal evolution, based on radiocarbon dating chronologies, has demonstrated that Australian coastal plains formed over the past ~6,000 years when sea level has been close to its present level, in contrast to several documented locations in the northern hemisphere where the sea has been rising for the past few millennia. Particularly insightful were observations by Davies that ridge formation could be influenced by a range of factors including changes in sea level, storminess, or sediment supply. These factors acting singly or in combination seem likely to change in the future. Understanding such responses remains a high priority and can be addressed by new technologies, such as light detection and ranging, optically stimulated luminescence dating, ground‐penetrating radar, and computer simulation.

Coarse‐sand beach ridges at Cowley Beach, north‐eastern Australia: Their formative processes and potential as records of tropical cyclone history

“…The lower extent of these truncation surfaces is generally obscured by the strong reflection of the groundwater table, but some clearly continue down to the discontinuity in the sequence of seaward‐dipping reflections in the lower facies (for example, around 120 m, 150 m, 230 m, 310 m, 530 m, 560 m, 600 m and 610 m of the profile; Figs and ), recording pronounced beach erosion. These stratigraphic features indicate that the beach‐ridge sequence at Cowley Beach records a ‘cut and fill’ pattern (Davies, ), where the fair‐weather swash deposition and berm building are punctuated by erosion during storm conditions (Oliver et al ., ).…”

“…A fine‐sand beach is likely to be eroded by storm waves, while fine‐sand ridges are generally formed with the welding of the longshore bar and/or building of the berm by fair‐weather swash, and then by the accumulation of aeolian sand (e.g. Hein et al ., ; Oliver et al ., ). Gravels, in contrast, are unlikely to be transported by wind, but can be built upward as a ridge by storm waves as the storm‐wave downwash loses its energy as a result of percolation of water on gravel beaches (Carter, ; Otvos, ).…”

Reply to: Punctuated transgression (?): Comment on Oliver, T.S.N., Donaldson, P., Sharples, C., Roach, M., and Woodroffe, C.D. “Punctuated progradation of the Seven Mile Beach Holocene barrier system, southeastern Tasmania”

“…We do not consider it appropriate to adopt a sea-level curve from New South Wales (NSW) and apply it in this way to Tasmania, and discuss this in more detail below. Furthermore, we do not consider it useful to compare the chronologies of beach-ridge deposition, as we have found that individual prograded barrier systems in southern NSW appear to have undergone considerably different patterns of progradation (Oliver et al 2017b;2017c).…”

“…Evidence for a Holocene highstand in Tasmania has been elusive (Lewis et al, 2013). Davies (1958;1959;1961) proposed higher sea levels during the Holocene using the crests and swales of stranded foredune ridges at several sites in Tasmania, and proposed a fall in sea level of ~1 m at Seven Mile Beach, Tasmania (see also Oliver et al (2017c) for discussion). Glacio-isostatic adjustment (GIA) modelling by Lambeck and Nakada (1990) implied no highstand in Tasmania noting the potential influence of Late Pleistocene uplift also suggested by Murray-Wallace & Goede (1991;1995).…”

Holocene shoreline progradation and coastal evolution at Guichen and Rivoli Bays, southern Australia

“…The Australian coastline, with its rich history of coastal studies and many examples of foredune ridge plains, would appear to be an ideal location to evaluate regional trends of Holocene coastal progradation. Recent reviews have tended to focus on sandy ridge formation and the potential to derive palaeoenvironmental information (Goslin and Clemmensen, 2017; Oliver et al, 2017a; Otvos, 2000; Scheffers et al, 2011; Tamura, 2012; Tanner, 1995; Taylor and Stone, 1996). This leaves significant scope for investigating the interplay of fundamental drivers of prograded barrier development and sandy shoreline behaviour such as sea-level changes and variation in sediment supply (Roy and Thom, 1981).…”