Topographic data and derived products for early martian oceans

Data description 1. Overview This archive contains the topographic datasets and mapped spatial patterns of water-formed landscapes used in the manuscript entitled “identifying the topographic signature of early martian oceans.” The primary goal is to provide elevation, slope, and curvature for Earth and Mars across multiple pixel scales, including the subset of detected shelf cells (points) interpreted in this study as a putative martian shelf. A detailed description of the processing workflow—including input datasets and their sources, preprocessing steps, resampling/gridding to common pixel scales, and calculation of slope and curvature, as well as martian shelf mapping—is provided in the Methods section of the associated manuscript. 2. Topographic data 2.1 Data products The archive includes the following categories: Point samples extracted from rasters (e.g., points representing extracted elevation and calculated slope and curvature at multiple scales: 2.5 km, 5 km, and 10 km per pixel). Vector layers consist of points converted from raster cells that meet our topographic and geomorphic criteria for a putative martian shelf. 2.2 File formats Vector data: shapefile (.shp/.shx/.dbf/.prj). Tables (.txt). 2.3 Parameter definitions and units Elevation: meters (m) Slope: degrees (°) computed from elevation gradients Curvature: output from ArcGIS curvature tool. ArcGIS reports curvature values in hundredths of a z-unit (sign convention: positive = convex, negative = concave; flat areas near 0). Note: we re-scaled curvature for plotting (e.g., multiplying negative values by −1 for interpretability), that transformation is only applied in derived tables/plots, not in the raw curvature rasters unless explicitly stated. 2.4. Limitations and known issues Curvature and slope values are sensitive to pixel scale, projection, and local noise; interpret curvature comparisons across resolutions with caution. Resampling may smooth topographic extremes (especially slope/curvature). Mapped/interpreted classes (e.g., “shelf”) reflect the criteria described in the manuscript and may evolve with future mapping. 3. Spatial and elevation data for the martian water-formed landscape The water-formed landforms dataset builds on published maps (see Methods in the paper) of valley networks, outlet canyons, depositional rivers, interpreted deltas, and two putative shoreline traces. We used these mapped features to extract landform elevations and assess how martian water-formed landscapes vary across space and elevation. 5. Contact For questions, please contact: Abdallah Zaki ([e-mail]) ORCID: 0000-0002-4030-2105 Affiliation: 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125, USA; 2Department of Earth and Planetary Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA