cratera

Cratera is a roughly circular depression on the surface of a solid body, produced by processes such as impact, volcanic activity, or collapse. The term is used in Portuguese and other languages as well as in English, with the same general meaning.

Most craters form when a high-velocity meteorite or asteroid strikes a surface, excavating material and creating a raised rim and a rounded interior. Larger craters may develop a central peak formed by the rebound of the ground after the impact. In contrast, volcanic craters arise from eruptions or the collapse of magma chambers; calderas are especially large depressions formed by collapse rather than a single explosive event.

Crater types are often distinguished by morphology. Simple craters are small and bowl-shaped, while complex craters are larger and feature terraced rims and, in many cases, a central peak. Some floors are flat or partly flooded by lava, creating lava-filled or flooded craters. Ejecta blankets, rays, and secondary craters around the rim help indicate origin and relative age.

On Earth, craters are frequently eroded or buried by sediments and tectonic activity, making many features difficult to recognize. In contrast, craters on the Moon, Mercury, Mars, and other bodies without active atmospheres or plate tectonics are often well preserved, providing valuable records for planetary geology. Crater counting and morphology are standard methods for estimating surface ages and geological histories.

Notable examples include Meteor Crater in Arizona (a well-preserved impact crater) and the Chicxulub crater in the Yucatán, linked to the mass extinction at the end of the Cretaceous period.