When compared to tide-dominated shelves, shelves swept by geostrophic flows are relatively understudied, yet geostrophic currents have the potential to construct substantial current-generated shelf bedforms. This paper examines the evolution of a series of bedforms encountered along the narrow Agulhas Current-swept northern KwaZulu-Natal shelf. Their evolution is placed in the context of progressive current impingement and variation in flows associated with the postglacial transgression and culminating in the present-day highstand.

Ultra-high resolution seismic reflection, multibeam, side-scan sonar and single beam data sets reveal several bedform scales and morphologies; wave ripples and shoreface-connected ridges are associated only with the inner shelf, and 2D and 3D very large dunes are more cosmopolitan and span the entire shelf sector. The inner shelf is marked by rock outcrop (aeolianite), surrounded by sandy sediment, grading seaward into sediment starved bedforms associated with bioclastic gravels. Where sufficient sediment exists in local depocenters, very large dunes form discontinuous fields along the outer shelf.

The seismic stratigraphy of the outer shelf reflects the effects of postglacial flooding by rising sea levels and increasing current impingement by the Agulhas Current. The Holocene wave ravinement surface is overlain by flat-lying strata (early dune development and dune amalgamation with first current exposure), in turn covered by hummocky, sub-horizontal aggrading beds (amalgamation), overlain by inclined cross-bedded packages (lee faces of the bedforms formed during migration and full current interaction).

Morphometric analyses show that for both the inner and outer shelf, no relationships exist between water depth, wavelength and spacing. Height to spacing (H/L) relationships are weak but nevertheless show a broadly positive trend. Bedform heights are lower on the inner shelf compared to the outer shelf, but bedform spacing is greater on the inner shelf, with a 40% overlap in H/L indices observed between the two areas. The departures in overlap can be linked to the competing offshore Agulhas Current and the inshore wave-dominated processes. Bedforms of the inner shelf plot below the global H/L mean and can be related to the more infrequent incursions of the Agulhas Current core. At the time of survey, the Agulhas Current was likely situated well offshore, resulting in reduced current activity in the survey area resulting in rounding of the dune crests, degradation of the dune crests and trough infilling. On the outer shelf, the H/L values plot above the mean global trend, suggesting vertical accretion due to the faster currents. Crest rounding and downlapping of the upstream lee faces onto the downstream stoss faces indicate dune degradation, which is related to a seaward location of the Agulhas Current at the time of survey.

与潮汐主导的陆架相比，地转流席卷的陆架研究相对较少，但地转流有可能构建大量由海流产生的陆架床形态。本文研究了沿厄加勒斯洋流席卷夸祖鲁-纳塔尔大陆架北部的狭窄的一系列床型的演变。它们的演变是在与冰后海侵相关的渐进式电流冲击和流量变化的背景下进行的，并最终形成当今的高位。

超高分辨率地震反射、多波束、侧扫声纳和单波束数据集揭示了几种床型尺度和形态；波浪纹和与岸面相连的山脊仅与内陆架相关，2D 和 3D 的超大沙丘更具国际性，横跨整个陆架区域。内陆架以岩石露头（风成岩）为标志，周围环绕着沙质沉积物，向海分级为与生物碎屑砾石相关的沉积物匮乏的床型。在局部沉积中心存在足够沉积物的地方，非常大的沙丘沿着外陆架形成不连续的区域。

外大陆架的地震地层反映了海平面上升和厄加勒斯海流对海流冲击的增加对冰后洪水的影响。全新世波浪谷地表被平坦地层覆盖（早期沙丘发育和沙丘合并与第一次当前暴露），依次被丘状、亚水平的堆积层（合并）覆盖，被倾斜的交叉层状包裹（背风面）覆盖在迁移和全电流相互作用过程中形成的床型）。

形态学分析表明，无论是内陆架还是外陆架，水深、波长和间距之间均不存在关系。高度与间距 (H/L) 的关系较弱，但仍显示出广泛的积极趋势。与外层架相比，内层架的床型高度较低，但内层架的床型间距较大，两个区域之间观察到的 H/L 指数重叠 40%。重叠的偏离可能与竞争的近海厄加勒斯海流和近海波浪主导的过程有关。低于全球 H/L 平均值的内陆架图的床形可能与更不频繁的 Agulhas Current 核心侵入有关。在调查时，厄加勒斯海流很可能位于离岸较远的地方，导致调查区当前活动减少，导致沙丘顶部变圆、沙丘顶部退化和槽填充。在外层，H/L 值绘制在平均全球趋势之上，表明由于较快的水流而导致垂直吸积。上游背风面的波峰倒圆和下游背风面向下重叠表明沙丘退化，这与调查时 Agulhas 流向海的位置有关。