Extraterrestrial impact events can produce an impact stratigraphical sequence consisting of impact melt-sheet in crater, proximal ejecta-blanket and tsunami nearby crater, and distal ejecta layer in distal sites. Physical and chemical features of impact-generated strata are different from those of sedimentary and volcanic origins. Studies on impact-related minerals, geochemical anomalies, impact microspherules and microtektites enable us to define frequencies, magnitudes and types of impact bodies of extraterrestrial impact events. Impact layers and ejectas may not only provide distinct event markers in high-resolution stratigraphical correlation, but also potential interpretations for the catastrophic changes and their causes of life and global environment.