In geology, a very large basin-shaped crater. Calderas are found at the tops of volcanoes, where the original peak has collapsed into an empty chamber beneath. The basin, many times larger than the original volcanic vent, may be flooded, producing a crater lake, or the flat floor may contain a number of small volcanic cones, produced by volcanic activity after the collapse.
Typical calderas are Kilauea, Hawaii; Crater Lake, Oregon, US; and the summit of Olympus Mons, on Mars. Some calderas are wrongly referred to as craters, such as Ngorongoro, Tanzania. + prikaži više

ETYM Latin crater, cratera, a mixing vessel, the mouth of a volcano, Greek krathr, from kerannynai to mix; cf. Skr. çrî to mix, çir to cook, çrâ to cook. Related to Grail, in Holy Grail.
A bowl-shaped depression formed by the impact of a meteorite or bomb.

Funnel-shaped hollow in an area of limestone. A sink hole is usually formed by the enlargement of a joint, or crack, by carbonation (the dissolving effect of water). It should not be confused with a swallow hole, or swallet, which is the opening through which a stream disappears underground when it passes onto limestone.
A depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof; SYN. swallow hole. + prikaži više