Short answers, pulled from the story.
The Descartes Highlands are located on the near side of the Moon, in the area surrounding Descartes crater, from which the feature takes its name. The region is characterized by an undulating highland landscape covered with craters of varying ages.
Apollo 16 landed at the Descartes Highlands in early 1972. Astronauts John Young and Charles Duke were the crew members who explored the surface there.
Apollo 16 found that the rocks in the Descartes Highlands are not volcanic in origin but are breccias composed of fragments from multiple lunar impacts. This disproved the pre-mission hypothesis that the region was shaped by viscous volcanic lavas.
The Cayley Formation and the Descartes Formation are the two major geological formations that dominate the Descartes Highlands. The Descartes Formation is composed primarily of highland plateau material, possibly debris from the impact that created Mare Nectaris.
Young and Duke visited Sudbury, Ontario, Canada, in July 1971 to study shatter cones. Sudbury is the site of a major ancient meteor impact that displays clear shatter cone geology, and examining it prepared the astronauts to recognize similar features on the Moon.
The Descartes site was selected over Alphonsus crater because it offered a concentration of both the Descartes and Cayley formations, two units that cover much of the lunar near side. Mission planners also prioritized obtaining highland material older than the Imbrium impact to illuminate the Moon's earliest geological history.