Estuarine facies models; conceptual basis and stratigraphic implications; discussion and reply

Were all trilobites fully marine? Trilobite expansion into brackish water during the early Palaeozoic

“…Each valley system has been subdivided into three zones: inner fluvio-estuarine, middle estuarine, and outer estuarine, following the conventional tripartite division of estuaries [15] (electronic supplementary material, tables S1 and S2). This division has been extremely useful to frame estuarine variability into facies models [15][16][17].…”

“…Each valley system has been subdivided into three zones: inner fluvio-estuarine, middle estuarine, and outer estuarine, following the conventional tripartite division of estuaries [15] (electronic supplementary material, tables S1 and S2). This division has been extremely useful to frame estuarine variability into facies models [15][16][17]. Each of these segments is characterized by a different combination and intensity of stressors; a longitudinal salinity gradient is developed from the inner freshwater to strongly brackish fluvio-estuarine zone to the less stressful (for marine organisms), slightly brackish to near-marine outer estuary.…”

“…Instead, their presence may indicate an ability to periodically migrate landwards reflecting some ecological advantage. By contrast to wave-dominated estuaries, which are semi-enclosed water bodies flanked seawards by a sand barrier oriented parallel to the shoreline, tide-dominated estuaries are characterized by outer estuarine sandbars perpendicular to the coast and multiple subparallel channels that connect the sea to the middle and inner estuary [15]. Marine animals may use these channels as major conduits, particularly during high tides.…”