Coastal to deep-marine geomorphic classification: A standardised framework and review of terms to support globally consistent mapping

Updated: 2026-06-21

Marine and coastal geomorphology is inherently interdisciplinary, involving the interpretation of landforms shaped by overlapping hydrodynamic, sedimentary, tectonic, and biogenic processes across diverse physiographic regions. As the United Nations Decade of Ocean Science aims to provide robust scientific information to address ocean challenges, geomorphic data is becoming an increasingly critical baseline resource to support evidence-based decision-making. Standardised, inter-jurisdictional geomorphic frameworks enable consistent terminology across scales. Though marine sub-discipline lexicons are generally well established, seabed geomorphology mapping encompasses terminological nuances that can hinder analysts working across disciplinary boundaries. To address these challenges, the International Seabed Geomorphology Mapping Working Group (ISGM) developed a marine and coastal classification framework using an Ocean Best Practice process that incorporates science-community input. This two-part approach separates morphological mapping (Part 1) from geomorphic interpretation (Part 2), constraining the uncertainty inherent to stratigraphic interpretation to a second step. In Part 1, 40 bathymetric shapes are mapped and classified using standardised Morphology Feature terms. In Part 2, a hierarchical framework and glossary of over 400 terms across 11 overlapping classes assigns geomorphic interpretation. The framework supports classification from Setting/Process through basic geomorphic units (BGU), types (BGU-T) and sub-types (BGU-sT), allowing users to tailor classification to available data quality and application needs. Implementation of the ISGM scheme is supported by open-access, machine-readable digital vocabularies, which standardise established terms without redefining them, and GIS tools. Applied examples demonstrate utility across global datasets. By integrating existing terminology into a standardised, hierarchical framework, the ISGM approach provides the first cross-class geomorphic framework capable of supporting consistent terminology from global to local scales. <b>Citation</b> R. Nanson, R. Arosio, J. Gafeira, M. McNeil, D. Dove, L.R. Bjarnadóttir, M.F.J. Dolan, A. Post, S. Nichol, Z. Huang, J. Guinan, O.M. Bialik, J. Webb, J. Wells, A.G. Carroll, Coastal to deep-marine geomorphic classification: A standardised framework and review of terms to support globally consistent mapping, <i>Earth-Science Reviews</i>, Volume 276, 2026, 105439, ISSN 0012-8252, https://doi.org/10.1016/j.earscirev.2026.105439.