Geology of the Taurus-Littrow valley floor.

The paper surveys the geology of the Taurus-Littrow valley which is located in a graben that is radial to Mare Serenitatis. The basalt fill is characterized; basalt extrusion in the valley continued until about 3.7 b.y. ago and was quickly followed by deposition of glass beads that formed a mantling unit of probable pyroclastic origin. The glass-bead unit in combination with the overlying regolith forms an unconsolidated surficial deposit with an average thickness of about 14 m. The components of the regolith are described. It is thought that most of the craters are part of a secondary cluster formed by projectiles from Tycho. Age estimates for the central cluster and the light mantle are presented.