The existence of terrestrial meteorite craters is determined by laws of accumulation and disappearance. Both crater lifetime and discovery probability are proportional to the area of the structure (D2). The distribution in age (T, year) and dimensions (D, metre) is defined by the inequality of . The available material on terrestrial craters allows the study of the time variation in the stream of large cosmic bodies striking the Earth. Over the last billion years the stream of crater-forming meteorites has decreased according to the law Tτ where τ ≤ 0.2. The absolute value of the flux can be determined from a complete investigation of a portion of the Earth's surface.