A two-part seabed geomorphology classification scheme: Part 2 – a geomorphic classification framework and glossary
Authors: Nanson Rachel , Arosio Riccardo , Gafeira Joana , McNeil Mardi , Dove Dayton , Lilja Bjarnadóttir , Margaret Dolan , Janine Guinan , Post Alix , Webb John , Nichol Scott 
Published: February 2023

Maps of seabed geomorphology provide foundational information for a broad range of marine applications. To be most effective, geomorphic characterisation of the seabed requires standardised, multi-scalar and interjurisdictional approaches that can be applied locally, regionally and internationally using the best available data. An ongoing collaboration between geoscience agencies in the United Kingdom (BGS), Norway (GSN), Ireland (GSI; UCC) and Australia (GA; LU) has focused on developing a new standardised approach to meet this need. Dove et al (2016) first described a two-part approach for mapping the geomorphology of the seabed. Part 1 was subsequently published as an open access glossary that includes an illustrated list of terms and definitions that primarily draw on the International Hydrographic Organization standard (Dove et al, 2020). Morphology maps are created by applying Part 1 Morphological terms to bathymetry data. Part 2 classifies these mapped &#160;shapes with their geomorphic interpretation; geomorphic unit terms are structured within 11 geomorphic Settings (Fluvial, Coastal, Marine, Glacial, Hard Rock) and Process (Current-induced, Biogenic, Mass movement, Fluid Flow, Karstic, Anthropogenic) categories. Consistent with Part 1, Part 2 terms are primarily sourced from established literature. The application of Part 2 requires further seabed data and/or contextual information and expert judgement, and is intended to constrain the uncertainty that is inherent to subsurface facies interpretation and prediction to this step. A draft version of Part 2 was the focus of a well-attended (>50 participants) workshop at the IAG&#8217;s International Seafloor Geomorphology Conference in Malta (July 2022: Nanson et al., 2022). Feedback from that workshop and from the broader community was integrated into a revised version of the report, which will be released early in 2023. &#160;We will demonstrate the application of this method to several worked examples from coasts, continental shelves and the deep marine, and thereby demonstrate the utility of the two-part approach for mapping the distribution of sedimentary facies that form in these diverse marine environments. &#160;

Dove, D., Bradwell, T., Carter, G., Cotterill, C., Gafeira Goncalves, J., Green, S., Krabbendam, M., Mellett, C., Stevenson, A., Stewart, H., 2016. Seabed geomorphology: a two-part classification system.&#160;
Dove, D., Nanson, R., Bjarnad&#243;ttir, L.R., Guinan, J., Gafeira, J., Post, A., Dolan, M.F.J., Stewart, H., Arosio, R. and Scott, G., 2020. A two-part seabed geomorphology classification scheme:(v. 2). Part 1: morphology features glossary. https://zenodo.org/record/4071940#.Y7tURodBxPY&#160;
Nanson, R., Arosio, R., Gafeira, J., Dove, D., Guinan, J., McNeil, M., Bjarnad&#243;ttir, L., Dolan, M., Post, A., Nichol, S., 2022. A two-part seabed geomorphology classification scheme: Part 2 Geomorphology - Version 0.9.