Speleology

Maple, birch, cedar.

Water is considered a renewable resource because it is naturally replenished through the water cycle, which involves evaporation, condensation, and precipitation. Oil, on the other hand, is a non-renewable resource because it is formed from organic matter over millions of years and cannot be replenished at the rate it is consumed.

The Krubera Cave, also known as Voronya Cave, is the deepest cave system on Earth, located in the Arabika Massif of the Western Caucasus in Abkhazia, Georgia. It reaches a depth of 2,197 meters (7,208 feet).

Dissolution of the limestone by rain & snow-melt water slightly acidified by absorbed atmospheric carbon dioxide. It oozes through the rock's joints, bedding-planes & other discontinuities from surface to rising (spring). Eventually these initial micro-conduits start to coalescence and develop discrete passages.

Speleology is the scientific study of caves, including their physical structure, formation, geological characteristics, and biological contents. Speleologists explore caves to understand their environment, history, and the processes that shape them. They may study cave formations, underground water systems, and the unique ecosystems that exist within caves.

A volcanologist studies volcanoes, including their activity, behavior, and impact on the environment. Volcanologists may study various aspects of volcanoes, such as eruptions, magma composition, and volcanic gases, to better understand and mitigate volcanic hazards.

Cave passages can be humid due to water seepage from the surrounding rock layers or the presence of underground streams and rivers. The lack of ventilation in caves also contributes to high humidity levels by trapping moisture in the air.

Some people un-familiar with caves or possibly a person advertising a cave will claim a pit is "bottomless." Usually you can't see the bottom of these pits, so their story is convincing. Also, they may throw a rock into the pit, it lands in soft dirt and doesn't make a sound, so some gullible people will believe them. The answer to the question is that most of these pits are not even a 30 meters deep. A person should not enter these pits without proper training on techniques for climbing long free-hanging ropes. There are thousands of caves where the pit could be 100 meter free-fall. and there are plenty more deeper than that. The Velebita Pit in Croatia is the deepest pit inside of a cave at 513 meters deep. You would be far safer rappelling off of a sky-scraper, than exploring a deep pit without training or the proper equipment.

A shawl is a calcite formation and forms when water runs down a gentle slope rather than falling straight to the floor.

See the link below for a good picture taken in the Jenolan caves near Sydney, Australia.

A karst specialist is a geologist who is expertized in Karst Geomorphology. This type of scientists study the conditions and the procedures that lead to the formation of karst in limestone rocks.

Glacio-speleology is the study of caves within glaciers. It involves exploration and research focused on understanding the formation, structure, and dynamics of glacier caves, as well as their unique ice formations and processes. This field helps researchers gain insights into glacier behavior and climate change impacts.

Some cave passages may break thru to the surface forming a sky-light. In the zone were the sunlight reaches the soil, trees can live for hundreds of years, growing up all the way out of the cave. Some caves that are large sinkholes have floors that are over an acre in size. It is like a mini-rainforest down deep in those caves.

Artificial light can be used to grow plants in caves. Commercial (or show-) caves sometimes have patches of algae growing near their lamps.*

Seedlings wash deep into caves and sprout, but they usually die off after a few weeks. But this can be a food source to tiny creatures that live in those passages.

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*Know collectively as "lampenflora" (German, lit. 'Lamp flora') and now regarded as a nuisance by many show-cave owners. Some show-caves arrange limited lighting, rather than leaving the flood-lights on all the time the cave is open for tours, to minimise such vegetation. The species are generally of ferns and algae introduced as spores on visitor's clothing or wafting in on air-currents.

A subterranean river passage can have water flowing in opposite directions due to complex geological formations and varying water sources. This phenomenon can occur when multiple water sources enter the passage at different points, leading to the flow of water in opposite directions within the underground system. Changes in elevation, pressure, and underground water currents can also contribute to this unique flow pattern.

Sedimentary deposits are thought to exist up to 9 kilometers deep. From 9 kilometers to about 18 kilometers metamorphic layers likely exist. However, temperatures would be very high, along with toxic gases like sulfur. So explorable cave passage at that depth is unlikely. Drill cores in Wyoming have found limestone nearly 26,000 feet deep. Can anyone verify if that Mississipian layer is soluble enough to form explorable caves?

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Caves at that depth are not very likely but may form by dissolution by very deep, acidic, geothermal fluids. The normal limit really is not ever so deep below the base level - the altitude of the resurgence for their formative streams. Although they can form deep "sumps" like the U-bend under a sink, the limestone formation's own depth sets the limit, whatever the rock below it. So although sedimentary rock may be 9km deep, the cavernous limestone is likely to be far less.

Also, it's not the solubility of the limestone that's the problem. It's the physical nature of the formation, the relationship to basement and cover rocks, and hydrology of its region that matter.

Caves do not form naturally in slate with the possible exception of sea-caves (and then would be inherently unstable) and shallow rock-shelters.

Slate mines (entirely artificial) can be very extensive but these are man-made.

Most of the world's caves are Karst features, i.e. primarily in Limestone. Karst caves need three materials: a soluble rock like Limestone or Gypsum, water and Carbon-dioxide (CO2). The last two combine to form a weak acid that dissolves the limestone. For a fuller account: The host limestone needs to be of appropriate physical structure and raised into hills, then subjected to reasonably consistent precipitation for many tens or hundreds of thousands of years. Limestone is a sedimentary rock of which the world's greater proportion was laid down in warm, relatively shallow, seas. The rock was laid in horizontal layers - Beds - separated by Bedding-planes which generally reflect geologically-brief changes in the environment. The suite of beds is known as a Formation, generally named after its "type area". Later continental uplift (tectonic processes) raise the formation along with its underlying rocks, usually tilting and folding it to at least some extent in the process. Since most rocks are brittle they cannot take much stress, and limestone beds crack into grids of fine fractures called Joints. The uplift and folding often also causes Faulting - major breaks with the rock mass one side of the Fault Plane being raised, lowered or moved horizontally past that on the opposite side. (Note: Plane - the "Fault Line" sometimes misused as a political metaphor is that of the fault-plane cutting the land surface.) Now we have the hills, next we need rain-water that has absorbed atmospheric CO2 to create Carbonic Acid (weak, natural soda water in fact!). It may be augmented by acids from the soil, too. This solvent permeates through all those joints, bedding-planes and faults; flowing very, very slowly under considerable pressure applied by its depth, from its sinks on the surface to its springs at the base of the formation. In doing so, it dissolves the limestone (chemical weathering), creating meshes of tiny micro-conduits that over many tens of thousands of years coalesce and capture each other to form cave passages. Once this happens, the rate of erosion can increase - though still to perhaps only a few millimetres per thousand years under generally temperate climates. A cave, or a series within a cave system, that still carries its formative stream is called "Active", and is still being developed. Surface changes such as the valley floor being lowered by erosion, or down-cutting within the cave by its stream, changes the water's route and the original, now dried-out, stream-way is called "Fossil" or "Abandoned". Such passages may be filled with silt left by floods as the main flow gradually abandons them; or may become richly decorated with Speleothems - calcite deposits such as stalactites and stalagmites precipitated from ground-water still oozing through the joints in the limestone above the cave. In time such passages may start to break down as there is no stream to dissolve away slabs falling from the roof as permeating ground-water attacks the rock above. In the end, surface lowering of the landscape as a whole, breaches and destroys the cave. Nothing is permanent in Nature! Caves in limestone are also parts of Karst Landscape. i.e. a landscape developed by the dissolution of limestone, giving surface features like Dolines, Limestone Pavement, and in the tropics, distinctive hills such as those represented in Chinese Willow-pattern images. 'Karst' is from the Slavic word 'Kras', the name for its world type-area. @@@@@ The above is purely an introduction to a vastly more complex and subtle series of processes, of course, and you need to refer to appropriate text-books on geology and cave studies to learn them. The scientific study of caves is Speleology - embracing geology, hydrology, biology, archaeology and other disciplines. Simply visiting caves to enjoy them for their scenery and the physical and mental challenges they present, is called Caving, though you can't study a cave unless you can negotiate its obstacles.

How DO.... and the adjective is superflous since caves are underground by definition! SO to answer:

For the specific geology and development of any individual cave you will have to read the appropriate research papers on that region and its karst features; but if it's a karst cave, as most are, the essentials are:

How Caves Form in Limestone

This is such a common question on 'Answers' I wrote this single reply! The technical terms are introduced by capital initials.

Most of the world's caves are Karst features, i.e. primarily in Limestone.

Karst caves need three materials: a soluble rock like Limestone or Gypsum, water and Carbon-dioxide (CO2). The last two combine to form a weak acid that dissolves the limestone. For a fuller account:

The host limestone needs to be of appropriate physical structure and raised into hills, then subjected to reasonably consistent precipitation for many tens or hundreds of thousands of years.

Limestone is a sedimentary rock of which the world's greater proportion was laid down in warm, relatively shallow, seas. The rock was laid in horizontal layers - Beds - separated by Bedding-planes which generally reflect geologically-brief changes in the environment. The suite of beds is known as a Formation, generally named after its "type area".

Later continental uplift (tectonic processes) raise the formation along with its underlying rocks, usually tilting and folding it to at least some extent in the process. Since most rocks are brittle they cannot take much stress, and limestone beds crack into grids of fine fractures called Joints. The uplift and folding often also causes Faulting - major breaks with the rock mass one side of the Fault Plane being raised, lowered or moved horizontally past that on the opposite side. (Note: Plane - the "Fault Line" sometimes misused as a political metaphor is that of the fault-plane cutting the land surface.)

Now we have the hills, next we need rain-water that has absorbed atmospheric CO2 to create Carbonic Acid (weak, natural soda water in fact!). It may be augmented by acids from the soil, too. This solvent permeates through all those joints, bedding-planes and faults; flowing very, very slowly under considerable pressure applied by its depth, from its sinks on the surface to its springs at the base of the formation. In doing so, it dissolves the limestone (chemical weathering), creating meshes of tiny micro-conduits that over many tens of thousands of years coalesce and capture each other to form cave passages.

Once this happens, the rate of erosion can increase - though still to perhaps only a few millimetres per thousand years under generally temperate climates.

A cave, or a series within a cave system, that still carries its formative stream is called "Active", and is still being developed.

Surface changes such as the valley floor being lowered by erosion, or down-cutting within the cave by its stream, changes the water's route and the original, now dried-out, stream-way is called "Fossil" or "Abandoned". Such passages may be filled with silt left by floods as the main flow gradually abandons them; or may become richly decorated with Speleothems - calcite deposits such as stalactites and stalagmites precipitated from ground-water still oozing through the joints in the limestone above the cave. In time such passages may start to break down as there is no stream to dissolve away slabs falling from the roof as permeating ground-water attacks the rock above.

In the end, surface lowering of the landscape as a whole, breaches and destroys the cave. Nothing is permanent in Nature!

Caves in limestone are also parts of Karst Landscape. i.e. a landscape developed by the dissolution of limestone, giving surface features like Dolines, Limestone Pavement, and in the tropics, distinctive hills such as those represented in Chinese Willow-pattern images. 'Karst' is from the Slavic word 'Kras', the name for its world type-area.

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The above is purely an introduction to a vastly more complex and subtle series of processes, of course, and you need to refer to appropriate text-books on geology and cave studies to learn them.

The scientific study of caves is Speleology - embracing geology, hydrology, biology, archaeology and other disciplines.

Simply visiting caves to enjoy them for their scenery and the physical and mental challenges they present, is called Caving, though you can't study a cave unless you can negotiate its obstacles. The enthusiasts are simply Cavers throughout the English-speaking world - you see "spelunkers" sometimes on 'Answers' but it's a 1940s word stuck together from Latin and Greek, and though originally used neutrally by US cavers it started to become derogatory in the 1960s.

The most significant dilution of seawater occurs at the mouths of rivers and streams, where freshwater flowing into the ocean decreases the salinity of the surrounding seawater. Additionally, melting ice caps and glaciers are other sources of dilution in polar regions.

When the rock above a cave collapses, it can form a sinkhole if the collapse creates a depression in the ground. This can sometimes lead to the formation of a sinkhole cave system underground.

By removing the rock.

Most caves are in limestone and the mechanism is chemical weathering by slightly-acidic ground-water flowing through, initially, the joints and other fractures in the rock mass, later the walls and floors of the passages, anddissolving the limestoneas it does so.

Vertical Caves either have entrances which you must go down using a rope (instead of going in horizontally) and for safety reasons specialized equipment like a harness, rappel rack or "figure 8", (although if you absolutely had to you could go down using a body rappel technique) or most of the sections in the cave are similar in which you have to use the same equipment to go down safely. These cave entrances or sections are called pits if you are touching the wall or pretty close to it, within a couple of feet to the wall. If you are in free fall the entire distance, which is to say the cave walls are nowhere near you and the only thing you can touch is the rope and your equipment, it is called a dome cave, both of which are vertical caves as well.

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To which I would add it's handy to be able to come back out, and most caves do not have convenient lower exits! That's done by a technique called "prusiking" - often spelt "prussiking" but the former is correct as it's from the inventor's name.

This entails climbing back up the rope you rappelled down, using "ascenders" (cam devices) attached to the harness and to foot-loops, and which slide up the rope but grip it when loaded. The effect is that of a ratchet. There are various different arrangements of rope-rigging, harnesses & ascenders, and other types of [rappel] descender as well as the rack, but the principles are the same.

Dr. Karl Prusik, the Austrian mountaineer who invented the method originally for rescuing oneself from crevasses, initially used a loop of cord tied in a special knot (the Prusik Knot) giving the same effect.

A point on terms: I stuck to the US term "rappel" above, but it's "abseil" here in the UK, and looks German / Austrian in origin, presumably from Alpine climbing.

We use the term "vertical caves / caving" but not "pit" and "domes". The vertical drop is called a "pitch" or a "shaft" irrespective of its dimensions and the caver's distance from the wall - I hadn't realised there is a distinction between "pit" and "dome" in US caving terminology.

Another difference is that the Fig-8 descender is not now used in UK and European "Single Rope Techniques" - it would not work very well! We use a rack or a "bobbin" descender, which works fairly similarly to a rack.

Hang Son Doong Cave is not longer than Mammoth Cave in Kentucky which is over 362 miles long. Instead Hang Son Doong Cave has the largest cave passage in terms of height and width measuring 200m high and 150m wide. The previous record holder, Deer Cave in Sarwark, Malaysia, which is 100m high and 90m wide.

Caverns are formed when rain, run-off, or surface water mixes with the topsoil, then Carbon acid and Carbon Dioxide mix with the soil where plants grow, making an acid so powerful that it eats away at the limestone that is underground; making cracks. Over millions of years, this process makes caves, which also concludes that caves are made up of lots of other caves.

Do they though.

I don't dismiss the possibility of micro-organisms that may corrode limestone, and microbes certainly help form soil acids that will contribute to the acidity of ground-water hence its aggressivity in contact with carbonate rocks; but I find the blanket assertion very hard to accept. Please cite your sources.

The bulk of rock removal in caves is by chemical weathering by carbonic acid: rain-water that has absorbed atmospheric CO2. Soil acids will contribute and these organic acids are fermentation products, but I would not regard the micro-organisms responsible as extremophiles.

My disbelief is compounded by your own question, because if you have proven evidence or can cite papers on microbial karst processes, you would not need to ask after such a assertive statement. You would know!

No: the animals can't chat because they've been dead for millions of years... :-) Try searching under "geology", "palaeontology" or "fossils" with "forum" after the name. How "good" any site you find is, will rather depend on your tastes and interests and level of knowledge.