| 09 Jul 2026
Geological controls on the formation and evolution of shoreface-connected ridges: new insights from the Stroombank sand ridge (Belgian coast)
Abstract. Shoreface-connected ridges are large bedforms of the lower shoreface that play a key role in sediment redistribution between the shelf and the coast, yet their origin and long-term dynamics remain debated and poorly constrained due to limited geological information. Here we integrate high-resolution acoustic data, sedimentological analyses, and new radiocarbon and optically stimulated luminescence dates to reconstruct the origin and evolution of the Stroombank, a shoreface-connected ridge on the Belgian continental shelf. The ridge consists of landward-dipping clinoforms overlying an irregular basal disconformity that locally truncates Pleistocene and Holocene deposits. Chronological constraints indicate that ridge development began ca. 1.3 ka ago, followed by sustained shore-parallel elongation and landward migration. We infer that initial ridge formation was fuelled by sediment derived from a waning late-Holocene tidal inlet, after which elongation and migration were maintained through sediment distribution within the active shoreface. We propose a formation model in which wave-driven cross-shore transport, combined with flood-dominant residual sediment transport, explains the coupled landward migration and alongshore elongation reconstructed in the internal architecture. The Stroombank is therefore interpreted as an actively evolving sedimentary body rather than a relict feature. This interpretation is supported by the coexistence of active and inactive (preserved) sectors within the ridge. The preserved inactive sector allowed us to date the inception of the ridge, while the occurrence of both active and inactive sectors indicates that ridge development is spatially heterogeneous and reflects a continuum from antecedent to active phases. These results demonstrate that shoreface-connected ridges can form composite geomorphic features controlled by the interplay of sediment supply, hydrodynamic forcing and shoreface retreat, and provide geological constraints to evaluate existing conceptual and process-based models of ridge formation and evolution.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Earth Surface Dynamics.
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