Palus Somni 14.1°N, 45.0°E

Palus Somni, ‘Marsh of Dreams’, is a diamond-shaped area, lying immediately west of Proclus. It is completely free from ejecta from the Proclus impact, and the ray system separates Palus Somni from Mare Crisium. Palus Somni extends c. 150 km in an east-west direction and appears to be an intermediate geological stage between a highland and a mare floor. The northern portion is rough and fissured, whereas the southern portion is relatively flat, smooth and level. Palus Somni shows conspicuous nuances of colour, which were formerly the subject of numerous geological studies.

Proclus 16.1°N, 46.8°E

Proclus is a very conspicuous, obviously five-sided crater 28 km in diameter. It lies in the western highlands, adjoining Mare Crisium. The crater walls are sharply defined and seem to be little eroded. The floor of the crater is rough and fissured, and the crater walls reach a height of 2.4 km above the crater floor. Proclus is undoubtedly one of the youngest craters. The asymmetric shape of the impact ejecta is visible when the Moon is 5 to 6 days old, and the illumination around Full Moon causes the ray system to be one of the brightest objects on the lunar surface. The longest ray runs northeast, right across Mare Crisium and is c. 600 km long (that is roughly the distance between Boston and Washington).