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Contemporary shore platform stromatolites (SPS) are becoming well known. We describe the physical environment and macrostructures from contemporary shore platform stromatolites (SPS) on the wave-dominated southeast African coast. This was then compared with Mesoarchaean (2.97 Ga) stromatolites from White Umfolozi (100 km inland). We use the Tinley Manor SPS occurrence as the basis for physical environmental comparison, but where necessary draw on evidence from other SPS environments. SPS and Mesoarchean Umfolozi stromatolites contain similar stromatolitic structures and wave deposits. The SPS environment is wave dominated and the occurrence of similar sedimentary structures associated with the Mesoarchean Umfolozi Stromatolites indicates a paleoenvironment associated with waves. The contemporary Tinley Manor SPS wave climate is robust and from this locality we have identified broad limits in which SPS can develop and be preserved. Applying this knowledge to the Mesoarchaean White Umfolozi stromatolites suggests that they formed in a protected wave climate where wave incursions were less frequent. Both these wave-influenced settings are/were subject to very-low siliciclastic-input. The frequency of marine sediment input appears to be a limiting factor on microbialite growth in both the contemporary SPS and Archaean examples.

The marine, Lower Permian Vryheid Formation contains a distinctive macrobedform suite. This comprises giant crossbeds up to 12 m thick (large dunes), masterbedded units up to 15 m thick (giant dunes), stacked masterbedded units 40 m thick (supergiant dunes) and a shelf stratigraphy up to 100 m thick. Tidal currents, augmented by an oceanic current, were responsible for bedform migration. Two categories of giant dunes are noted: (1) a fine-grained-type (associated with tidalites and tempestites) which forms a sheet sandstones, and (2) a coarse-grained-type (associated with tidalites) which occurs as discrete pods. It is suggested that the distal fine-grained-type formed in a setting exposed to oceanic storms whereas the proximal coarse-grained-type developed in a sheltered setting. With migration into more open areas the coarse-grained-type could develop into the fine-grained-type. It is further suggested that the giant dunes climbed to form supergiant dunes up to 40 m thick. The supergiant dunes are further stacked into stratigraphic units 40–100 m thick which may be due to supergiant dune climbing, or possibly tectonic effects, to produce a regressive shelf sequence.

Sandstones and siltstones of a giant cross-bed sedimentary association at the base of the coal-bearing Vryheid Formation cannot be satisfactorily explained in terms of the currently accepted fluviodeltaic model for these strata. In view of the sedimentary structures and associational characteristics of the facies, a shoreface ridge interpretation is adopted instead. The sandridge, probably detached from the shoreface, was situated on the slope towards the basin plain and associated with some elements of a minor submarine fan complex. Rapid shoreface by-pass in the course of a marine transgression seems to have provided favourable conditions for sandridge formation. The major bedform appears to have been in water of about 45 m depth, possibly some kilometres from the contemporary shoreline. There is evidence that it was mainly constructed by the action of strong, easterly flowing currents, probably of relaxant or geostrophic origin. These were aided by ebb-dominant tidal currents. Possible actualistic models include North Sea and Bering Sea sandridges. Currents of the strength needed to build such large bedforms could only have existed in an open-ended seaway and it is suggested that the Ecca sea must have communicated, at least intermittently, with open ocean to the northeast and possibly the southeast as well as towards the west.

As a result of railway excavations the Pietermaritzburg Shale-Vryheid Formation transition is spectacularly exposed on the southern slope of Zungwini Mountain. Nine facies and three facies associations are recognised. Deposition occurred in a palaeoshelf and offshore setting. The reconstructed coastline was SW-NE with land to the northwest. The inner shelf was tide- and the outer-shelf storm-influenced. Fluvial input supplied sediment which was reworked into flood-tidal sandwaves, probably within the confines of an estuary. A rising sea level brought the sandwaves into the realm of a more distal, coast-parallel, storm-tidal current regime where reworking of the sediment occurred. Intense storm-augmented tidal currents swept some of the better-sorted material seaward to be deposited as storm layers in the inner and outer shelf. These same currents formed the low-density turbidites and sediment plumes from which the offshore argillaceous deposits were formed. The shelf edge poorly sorted rhythmite facies may have developed from sediment flushed out of the rivers during flood or from the flood-tidal sandwave system as a result of exceptional coastal storms.