In a few cases meteorite fragments are found associated with the crater. These and other clues, often found together, have ruled out the usual geologic alternatives such as old volcanic craters, natural basins, etc. Traditional geology stands vindicated. Obviously, the major strata of the geologic column have been laid down over the ages. Those ages have seen the impact of many large asteroids, each in itself a rare event.
Major impacts are obviously rare, being that none have occurred during recorded history.
Therefore, creationists must conjure up a miraculous swarm of asteroids which decide to drop in on Earth throughout the year of Noah's flood. They fall here and there without destroying the ark with milehigh waves or blast effects far exceeding that of any atomic bomb. After the flood dries up this bunch of asteroids, which had been steadily bombarding the earth and creating miraculous numbers of craters, suddenly decides to pack up and go home. Thus, history knows of not one large impact in the thousands of years since that one, magical year. The geologic column stands vindicated.