The Aristarchus-Harbinger region of the moon - Surface geology and history from recent remote-sensing observations

Photographic and remote sensing observations made from earth and Apollo orbiting spacecraft were used to study the Aristarchus Plateau-Montes Harbinger region. The appearance of the area is described, and a delineation of geologic map units and their stratigraphic relationships is presented. Physical and chemical properties of certain of the geologic units are deduced, and the interrelationships between materials of volcanic and impact origin, including the effects of excavation, redistribution, and mixing of previously deposited materials by younger impact craters, are discussed. A detailed geologic history of the region is developed. Attention is directed to the anomalous red dark mantle on the plateau; it is thought that this layer consists of fine-grained block-free material containing a relatively large fraction of orange glass, and that this layer is probably of pyroclastic origin, laid down at some time during the Imbrian period of mare flooding.