What are ways in which limestone caves are useful?
One in Ohio, as i recall reading in Popular Mechanics years back ( sixdties or seventies) was converted into a huge, underground Mushroom farm, originally it was a man-developed Limestone mine . so there are applications to general commerce.
Old limestone mines -or underground quarries as they are sometimes termed - are used for various purposes such as mushroom farms as you say, or forstores, as well as being visited in their abandoned state for their industrial-archaeology interest.
However the question is about caves, not mines. They are (present tense) in the way any landscape feature is useful, as a part of nature to be respected and admired, whether as show-caves or left unaltered for recreational caving and cave-studies.
A cave that is still "active", i.e. carrying its formative
stream is useful as a part of the natural water-supply for its
location, for it brings water from the hills to the spring that is
A cave is also valuable as a wildlife habitat in various ways.
Caves are generally natural by definition! In prehistoric times and depending on their locations and characteristics some caves were used as homes and/or ritual sites by early tribes. Others were no doubt useful as dens for wild animals. Don't forget though that firstly, most caves are only in limestone uplands so only useful to those living in the area; and secondly, most caves are not habitable.
Limestone caves are created through the process of erosion by water. The erosion follows chemical weathering: the water dissolves the limestone. A karst landscape is formed when water flows through soluble rocks such as limestone, dolomite and gypsum. Limestone dissolves away through the reaction of water.
I think I know what you mean. The vast majority of the world's caves are formed in limestone by water dissolving the calcium carbonate that is the rock's main constituent. As for "type", well, almost any "type" by age or source of limestone physically capable of supporting itself above the developing void. Caves will also form in marble (metamorphosed limestone) and in gypsum (calcium sulphate), in the same way. So the limestone is not "often…
Most caves are in limestone, which is slightly soluble in rain-water acidified by carbon-dioxide absorbed from the atmosphere. This weak "carbonic acid" corrodes the limestone as it flows through the rock's joints, bedding-planes and faults fromsinks to risings (springs). There are other caves formed in other ways, such as lava-tubes and mass-movement fissures. Oh - and by definition caves are underground - you don't need the adjective!