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(Freely adapted from Wikipedia)
Catharina is an ancient lunar impact crater (dia. 100 Km, dep. 3.1 Km) located in the southern highlands. It lies in a rugged stretch of land between the Rupes Altai scarp to the west and Mare Nectaris in the east.
With the large craters Cyrillus and Theophilus in the north, Catharina forms a prominent grouping that is framed by the curve of the Rupes Altai. Together they form a notable feature when the Sun is at a low angle to the surface. There is also a distinct difference in the ages of these three craters, with the age increasing significantly from north to south.
The rim of Catharina is heavily worn and irregular, with most of the north wall incised by the worn ring of crater Catharina P. The northeast wall is deeply impacted by several smaller craters. No terracing remains on the inner wall, and the outer rampart has been nearly eroded away. The floor is relatively flat but rugged, with a curved ridge formed by Catharina P, and the remains of a smaller crater near the south wall. Nothing remains of a central peak.
Cyrillus is a lunar impact crater (dia. 98 Km, dep. 3.6 Km) located on the northwest edge of Mare Nectaris. Intruding into the northeast rim is the slightly larger, and younger crater Theophilus. Together these three craters form a prominent trio in the southeast quadrant of the Moon. Cyrillus is named after Saint Cyril of Alexandria, a 4th-century Coptic Pope and theologian.
The floor of Cyrillus contains a reduced central hill and the considerable crater Cyrillus A. The walls of the broken formation of Cyrillus remain intact up until the point of junction with Theophilus. Slightly northeast of its center, three rounded mountains rise to heights of 1,000 metres above Cyrillus' floor: Cyrillus Alpha, Delta, and Eta.
Theophilus is a prominent lunar impact crater (dia. 100 Km, dep. 3.2 Km) that lies between Sinus Asperitatis in the north and Mare Nectaris to the southeast. It partially intrudes into the comparably sized crater Cyrillus to the southwest. It was named after the 4th-century Coptic Pope Theophilus of Alexandria.
The rim of Theophilus has a wide, terraced inner surface that shows indications of landslips. It is 14,000 feet deep with massive walls and has broken into a second formation, Cyrillus. It has an imposing central mountain, 1,400 meters high, with four summits.
The floor of the crater is relatively flat, and it has a large, triple-peaked central crater that climbs to a height of about 2 kilometers above the floor. The western peak is designated Psi (ψ), the eastern Phi (φ), and the northern peak is Alpha (α) Theophilus. The western slopes of this ridge are wider and more irregular, whereas the peaks descend more sharply to the floor on the northern and western faces.
The Apollo 16 mission collected several pieces of basalt that are believed to be ejecta from the formation of Theophilus.
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