The terrestrial cratering record. I - Current status of observations

The location, size and principle characteristics of the currently known proven and probable terrestrial impact craters are compiled. A crater is classified as proven if the structure is associated with meteoritic fragments, and probable if shock metamorphic effects are observed in the target rocks. Proven impact structures have been found to be Pleistocene to Recent in age, while probable impact structures range from Precambrian to Pleistocene. Diameter and age relationships are used to show that a 20 km impact structure will be recognizable as a crater for up to 600 million years, and smaller structures will have shorter lifetimes. Depth-diameter relationships for terrestrial craters show them to be intrinsically shallower than their lunar counterparts, and a transition in crater morphology from simple, or bowl-shaped with an uplifted rim, to complex, with an uplifted center and a depressed rim, is observed with increasing diameter. Shock metamorphic studies have lead to the identification of the type of bolide at a number of probable impact craters, supporting meteoritic origins.