Impact craters (>500 m) in Oxia Planum classified by there degradation state.

This data set contains impact crater rims digitized as vector polygons in ESRI ArcMap 10.1 Geographic Information System Software to the CTX mosaic data and categorised based on 4 aspects of their morphology: the rim, ejecta, cross-sectional shape and stratigraphic relationship and assess their relative degradation state to what would be expected for a fresh impact crater in Oxia Planum.

Impact crater rims were drawn with vertex spacing of 25 m at a scale of 1:15,000. In cases where the crater rim was removed, or artefacts in the CTX mosaic obscured the rim, a best estimate was made based on a circular perimeter. As this is qualitative analysis, consequently there may be random errors associated with the digitization. In particular, craters which are embedded or overlying with surficial deposits can be quite similar (e.g.; Table 1, rows 2 and 3). Identification and digitization errors can occur from the CTX image mosaics. Errors arise from inconsistent georeferencing and colour balance compared with the original CTX images. In particular, when an impact crater was positioned on an image seam, parts of or the entire crater could be lost due to stitching. To mitigate against this we used the original mosaiced CTX images for classification and THEMIS to correct for errors in position. In addition, as only visual identification was used to identify ghost craters <10km, there may be a larger number of ghost craters which could not be identified without the topographic data available at that scale.