Formation and geography working next to
Tracy's Rock in the Taurus–Littrow valley on the
Apollo 17 mission in 1972. The South massif is visible to the right. Several million years after the formation of the Serenitatis basin,
lavas began to upwell from the Moon's interior, filling the basin and forming what is now known as Mare Serenitatis. As a result of these lavas, rock and soil samples from the area that were collected by Apollo 17 astronauts
Eugene Cernan and
Harrison Schmitt provided insight into the natural history and
geologic timeline of the Moon. Along the South Massif lies Bear Mountain, named after a mountain of the same name near Harrison Schmitt's hometown of
Silver City,
New Mexico. The sculptured hills and East massif make up the eastern edge of the valley and to the west, a
scarp cuts across the valley floor and rises about above it. The North and South massifs funnel into the main outlet of the valley, which in turn opens to Mare Serenitatis, such gap partially blocked by Family mountain. Based on Apollo 17 observations, the valley floor is generally a gently rolling plain. Boulders of various sizes, together with other geologic deposits, are scattered throughout the valley. At the
ALSEP lunar experiment deployment area, located west of the immediate landing site, the boulders average about four meters in size and are higher in concentration than in other areas of the valley. The
Tycho impact, which occurred between 15–20 and 70–95 million years ago, formed
secondary crater clusters in various locations of the Moon. Data from the examination of these clusters suggest that the central crater cluster in the valley formed as a result of that impact. Analysis of known secondary impact clusters resulting from the Tycho impact reveals that the majority of them have a downrange
ejecta blanket, or debris layer, with a distinctive 'birdsfoot' pattern. Apollo 17 observation data and comparison between the valley's central crater cluster and known Tycho secondary impacts indicate many similarities between them. Above the layer of subfloor basalt lies a deposit of unconsolidated material of various compositions ranging from volcanic material to impact-formed regolith. and has been the subject of
thermochronological calculation in an effort to determine whether the Moon generated a
core dynamo or formed a metallic
core, an inquiry that has yielded results in apparent support of the former—an active, churning core which generated a magnetic field, manifested in the magnetism of the sample itself. Further analysis by Garrick-Bethell et al. of the sample reveals nearly unidirectional magnetism—perhaps parallel to that of a larger field—lending further support to the hypothesis that the sample's magnetic properties are the result of a core dynamo in lieu of a singular shock event acting upon it. Rocks sampled in the immediate vicinity of the
Lunar Module are mostly
vesicular coarse-grained subfloor basalt, with some appearance of fine-grained basalt as well. Much of the valley floor, as indicated by observations of the immediate landing area, is made up of regolith and fragments varying in sizes excavated by several impacts in the Moon's history. ==Landing site selection==