Table 1. Morphological classes Lunar craters (A–C)

Class	Geomorphological characteristics	Relative depth	Max.Inner slope angle
A	Very steep slopes; clearly defined rim; prominent blocky ejecta zone.	1/3–1/5	35°–45°
AB	Steep slopes; sharply defined, slightly flattened rim; discernable ejecta zone with common blocks.	1/5–1/7	25°–35°
B	Moderately steep slopes; smoothed rim outlines; blocky material infrequent except on the rim.	1/7–1/10	15°– 25°
BC	Gently sloping; poorly pronounced rim; outer surface nearly indistinguishable from inter-crater space.	1/10–1/12	10°–15°
C	Very gently sloping; minimal relief; rim and crater surface differ very little from surrounding terrain.	< 1/12	< 10°

Data from Basilevsky (1974).