The lunar highlands are the remnants of the primordial crust exposed the moon, and it recorded this billions of years of solar system history. Since its formation, both impact craters and volcanic processes controlled the landscape of the lunar highlands. The attached photo shows a region of typical plateaus north of Mare Nectaris which highlights Vallis Capella.

The fundamental principle of geoscience is the superposition (young characteristics overlap older features) and this is as applicable on the Moon and other planets as it is here on Earth. Planetary scientists can use images like this to establish a sequence of relative time for placement of relief forms.

After the formation of the Moon in a giant impact, rich anorthosite crust was exposed to a prolonged period of heavy bombardment by asteroids and comets that formed the large lunar basins. Studies of the samples brought back by Apollo astronauts show that Nectaris basin (containing Mare Nectaris, visible in the lower left corner of the photo) was formed by an impact that occurred about 3.92 billion years ago. The heavily cratered surface in this scene is essentially a primordial remnant lunar crust in the middle of Necatris (South), Tranquillitatis (north), and Fecundidtatis (east).

Subsequent smaller impacts the formation of Nectaris formed the Capella and Isidorus craters. Capella (49 km diameter) slightly intrudes on Isidorus eastern edge showing that Capella is the younger of the two. The promontory in southeast Capella crater is probably a result of formção of Vallis Capella, passing directly through the Capella crater going from the North Rim to the southeast rim, and extending out on both sides to a total distance of about 110 km. Plausible explanations for the origin of Vallis Capella include the formation of a chain of impact craters (catena), tectonic extension after the formation of the giant basins surrounding this region, or as filling the Nectaris increasing its mass below the crust. Later, basalts filled the basin Nectaris and infiltrated a part southeast of Vallis Capella. Later still, the smaller impact craters formed many of 10-15 km in diameter. It is one of the most pristine Isidorus A, located within the old Isidorus and which is barely visible in the photo. The most recent craters (the last few hundred million years) are no larger than a few kilometers in diameter and has the brightest blanket of ejecta, as the crater indicated by an arrow.

A bonus part in the photo are the remarkable Gutenberg and Goclenius craters with her Rimae system.

Source: Arizona State University - Apollo Image Archive

Adaptation and text: Avani Soares