Established and Supposed Examples of Meteoritic Craters and Structures

Meteor Crater of Arizona, three-quarters of a mile across and' six hundred feet deep,, with its walls of tilted and faulted strata and its encircling high rim of pulverized and brecciated rock, is a spectacle for the student of land forms, of geologic structures, and of katamorphic processes. Standing on its rim, one is imp,ressed by the fact that craterforming meteorites are extraterrestrial agents that are truly catastrophic in their geological effects. However, the relative importance of giant meteorites among the agents that shape the landscape and deform or break rocks depends upon the distribution of meteorite scars in space and time. At present no one can say how many meteorite craters are to be found on the face of the earth; nor can one say how many scars recording geologically ancient falls exist in the rock layers of the crust. But it is significant that the number of recognized' craters is rapidly increasing.