Trace of Fallback Breccia on the Rim of Barringer Meteorite Crater (a.k.a. Meteor Crater), Arizona.

Barringer Meteorite Crater (aka Meteor Crater), Arizona, is one of the youngest and best preserved impact craters on Earth. For that reason, it provides a baseline for similar craters formed in the geologic past, formed elsewhere in the Solar System, and illuminates the processes that form them. The crater has not, however, escaped erosion completely. While Shoemaker [1] mapped a breccia with fallback components inside the crater, he did not locate it beyond the crater rim. He only found remnants of that type of debris in reworked alluvium [1; see also 2]. Fallback breccia and any base-surge deposits have, thus, been missing components in studies of material ejected beyond the transient crater rim.
Relics of that type of material began to emerge (Fig. 1) in a new mapping effort. In a series of NASA-sponsored student training and research programs, that material and related ejecta mechanics are being systematically documented [3-8]. Here, we present the latest results, which indicate traces of fallback breccia survive on the crater rim.