11. This is a relatively fresh feature that has not been significantly worn through impact erosion . 12. This is a relatively fresh crater formation that has not been degraded through impact erosion . 13. The rim and inner walls are rounded from impact erosion , and have lost some definition. 14. It has a well-formed edge that has not been noticeably degraded through impact erosion . 15. The rim is not significantly worn due to impact erosion , and the edge remains sharp. 16. This crater has been worn by impact erosion , leaving the features rounded and somewhat irregular. 17. This crater has a deteriorated outer rim that has been worn down and reshaped through impact erosion . 18. This crater has undergone a degree of impact erosion that has left its features softened and rounded. 19. This crater has a well-defined outer rim that is only mildly worn by impact erosion . 20. This crater has a well-defined rim that has not suffered much wear from impact erosion .
