Kraška jama je naraven izvotljen prostor pod zemeljskim površjem, ki nastane na kraškem svetu. Jama nastane kot posledica geoloških procesov, tektonskih premikov, delovanja vode in drugih atmosferskih vplivov na apnenčasto podlago. Kraške jame imajo lahko obliko brezna ali so vodoravne. Vodoravne kraške jame so nastale pod vplivom korozije, oblikovale pa so jih tudi podzemne reke (erozija). Glede na prisotnost podzemne reke ločimo vodne jame in suhe jame. Vodoravne jame lahko segajo v več nadstropij.
glej: _ brezstropa jama
Karst cave. A karst cave is a cave usually formed in soluble rock such as limestone. It is the most frequently occurring type of cave. It can also form in other rocks (solutional cave), including chalk, dolomite, marble, salt beds and gypsum. Rock is dissolved by natural acid in groundwater that seeps through bedding-planes, faults, joints and so on. Over geological epochs these openings expand as the walls are dissolved to become caves or cave systems. The largest and most abundant solutional caves (karst caves) are located in limestone. Limestone dissolves under the action of rainwater and groundwater charged with H2CO3 (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst, characterized by sinkholes, and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. These include flowstones, stalactites, stalagmites, helictites, soda straws, calcite rafts and columns. These secondary mineral deposits in caves are called speleothems. The portions of a solutional cave that are below the water table or the local level of the groundwater will be flooded.
see: _ roofless cave