Geological Chronicle
Taurus-Littrow is an elongated lunar valley along the southeastern rim of Mare Serenitatis, bounded by the towering North and South massifs whose relief exceeds the depth of the Grand Canyon. The enclosing mountain ring formed roughly 3.8 to 3.9 billion years ago when the impact that excavated the Serenitatis basin thrust crustal rock outward and upward. Subsequent volcanic activity filled the lowlands with basalt flows, leaving a valley floor that spans a feature diameter of 21.03 kilometers underlain by dense basalt sheets exceeding 1,400 meters in thickness.
During the Apollo 17 expedition in December 1972, astronauts Eugene Cernan and Harrison Schmitt targeted the site to sample ancient highland crust alongside volcanic deposits. Surface investigations revealed that the massifs consist primarily of feldspar-rich breccia, while the dark floor is blanketed by an unconsolidated regolith layer roughly 14 meters thick. Pyroclastic eruptions that accompanied the flooding of Serenitatis deposited widespread volcanic glass beads, including the striking orange soil discovered at Shorty crater.
The geological record in the valley also incorporates debris transported from distant events across the Moon. Impacts linked to the crater Tycho distributed secondary crater clusters and triggered an avalanche that spread a 6-kilometer debris apron known as the light mantle across the southern floor. Among the surface samples retrieved from the valley was Troctolite 76535, a 4.25-billion-year-old rock whose remnant magnetism indicates that the early Moon generated an internal core dynamo.