Simple Crater

Smallest impact features, consisting of a bowl-shaped interior with smooth walls, an elevated rim, and a
shallow inclination hummocky exterior. The interior wall is usually inclined at 20-40° to horizontal, whereas the exterior wall is inclined at 5-15° to horizontal. At larger diameters, simple craters become more complex with transitional forms developing in the 15-25 km diameter range on the Moon, 4-10 km range on Mars and 2-6 km range on Earth. Transitional craters have landslides
on the interior wall and a hummocky floor. The photograph shows Moltke on the Moon, a typical simple crater. The crater diameter (measured across the top of the rim) is 6.5 km and the crater depth (measured from the top of the rim to the centre of the floor) is 1.3 km.

Cropped from image source: