Classification of Caves

Definition: A cave is an airfilled underground void, large enough to be examined in some way by man.

There are very different types of caves, which can differ in several characteristics. To structure this diversity, caves are divided into classes. For this purpose, different criteria are used, which also lead to different results. We would like to present the most common classifications here.

  1. by the rocks they are in Only the rock is considered, not the mechanism by which the cave was created. A limestone cave for example is not necessarily a karst cave.
  2. By the morphology of the cave, the geometric structure
    • horizontal caves consist of some nearly horizontal tubes.
    • fissure caves consist of a single fissure or cleft in the rock.
    • vertical caves consist of shaft(s) and short links in between.
    • cave systems are rather large a contain many different features.
    • through caves are are cave ruins, where only a short piece of passage remains which is open on both ends, so you can walk through.
    The discrimination in horizontal and vertical caves is useful only in areas with rather small caves. Those caves consist normally of a single tunnel or shaft. In other karst areas with larger caves, any cave is a cave system. So while this classification is very commonly used in some karst areas, it is actually of no scientific significance.
  3. by the time they were formed, in relation to the forming of the rocks they are in:
    • primary caves are formed together with the surrounding rocks.
    • secondary caves are formed (long) after the formation of the rock. There is a second stage when part of the rocks are removed and the caves created. The mechanism of the transport of removed material is not relevant for this classification.
    • tertiary caves are the result of the collapse of other caves or subterranea.
    The first two terms are widely used, the last is almost unknown, and actually such caves are extremely rare.
  4. by the way they were formed:
    • solutional caves: rocks like salt and gypsum easily dissolve in normal water.
    • karst caves: most caves are in rocks which can be dissolved by a weak natural acid (usually carbonic acid). This acid forms when rainwater absorbs CO2 from the air and the upper layers of the soil. Other acids are produced by microorganisms and the water absorbs them when it seeps through the soil.
    • lava caves: are formed inside lava, which is molten rock. They form before or while the lava cools down and solidifies.
    • tufa caves: when limestone rich water emerges from a spring, the limestone is deposited around the spring, and sometimes it grows irregular and encloses empty spaces.
    • erosional caves: are created by erosion, mechanical weathering and relocation of material by water or wind.
    • tectonic caves:
      • Talus (ta'les) Caves: large landslides lead to the formation of boulders, whereby large cavities can develop between the sometimes quite large boulders.
      • Fissure Caves: on valley slopes of stratified rocks, erosion of the lower layer often causes the upper layer to slide down. This causes widening fissures.
      • Neotectonic caves: a special form of tectonic caves that occurs almost exclusively in Scandinavia. They are created by tectonic forces in connection with the pressure relief caused by the melting of the glaciers of the ice age.
      • incasion caves: formed by the collapse of cavities.
    • glacier caves: by the melting of ice, the water moving through glaciers brings warmth from outside. This caves are formed only inside the ice of glaciers.
    • soil tubes: in desert areas, flash floods can move through the soil and create slot canyons and caves.
  5. by the age of the rock: this is useful for karst caves. Sedimentary rock and is characterized by the time it was formed. Since the end of the Precambrian limestone was continually formed somewhere on Earth, so any geologic strata since the Cambrian may give its name.
  6. By the time of cave formation: this is useful for karst caves. This works because karst caves are formed while the rocks are exposed. Down- and uplift will stop and restart karstification
    • Cretaceous karstification.
    • Tertiary karstification.
    • Quaternary karstification.