Impact craters

circular depression in a solid astronomical body formed by the impact of a smaller object

fine ejecta

type of crater whose relief has disappeared

method for planetary surface chronology

geological feature

alt=|thumb|322x322px|Purple and green pseudotachylyte veins in outcrop (Sierra Nevada Mountains, California) Pseudotachylyte (sometimes written as pseudotachylite) is an extremely fine-grained to glassy, dark, cohesive rock occurring as veins that form through frictional melting and subsequent quenching during earthquakes, large-scale landslides, and impacts events. Chemical composition of pseudotachylyte generally reflects the local bulk chemistry, though may skew to slightly more mafic compositions due to the preferential incorporation of hydrous and ferro-magnesian minerals (mica and amphib

impact crater formed by the ejecta that was thrown out of a larger crater

permanently shadowed region of a body in the Solar System

inner edge of an impact crater that often extends above the local surface

large impact crater morphology with uplifted centres

Depth of an impact crater

crater containing multiple concentric topographic rings