Speleology

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.

Harrison's Cave in Barbados was formed over thousands of years through the process of water erosion and chemical weathering. Rainwater mixed with carbon dioxide creates a weak carbonic acid that dissolves the limestone rock, creating underground cavities and passageways. As the water flows, it deposits minerals, forming the unique stalactites and stalagmites that can be seen in the cave today.

Stalactites hang from the cave ceiling, formed by mineral deposits dripping from above. Stalagmites rise from the cave floor, created by mineral deposits building up from the ground. When a stalactite and stalagmite meet, they form a column.

The Precambrian time, which includes the majority of Earth's history, began approximately 4.6 billion years ago with the formation of the Earth. This time period encompasses about 88% of geologic time and is divided into the Hadean, Archean, and Proterozoic eons.

The vast majority of the world's caves are in limestone, due to that rock's solubility in weakly-acid water, so lie within limestone uplands offering suitable combinations of structural, hydrological and long-term climate controls favourable to cave and other karst feature development.

Lava Tubes are found in some basalt lava flows - e.g. on Iceland & the Canary Islands.

Mass-movement caves occur behind cliff-faces and valley walls under certain conditions - they are landslip features.

There are few other type of minor caves dotted around in various other rocks, too.

When the roof of a cave wears away and the ground sinks in, it forms a sinkhole. Sinkholes are depressions or holes in the ground that are typically caused by the collapse of surface material into underground caves or voids.

No one benefits from earthquakes. They result in loss of lives, damage to infrastructure, and economic disruptions. Governments, relief organizations, and communities work to provide aid and support to those affected by earthquakes.

Apart from accidentals that fall or are washed into caves, and rarely survive for long there, there are two categories.

1) Creatures like bats who roost, hibernate or nurse their young in caves but feed outside. Others find cave entrance areas pleasant shelter for safety or for habitat reasons.

2) Full cave-dwellers, living their entire lives underground, and generally unable to survive outside. Most are invertebrates but it includes some species of salamander and fish.

Solid limestone may change into a cave when it is dissolved by acidic rainwater or groundwater over long periods of time. The water dissolves the limestone, creating underground voids and passages that eventually form a cave system. Other factors like tectonic activity or volcanic activity can also contribute to cave formation in certain circumstances.

In all limestone caves, the same as as is "evident" - by the cave's very existence - as in all the limesrtone caves and other karst features in your country - chemical weathering! (Dissolution by carbonic acid.)

SPELEOTHEMS: Stalactites, stalactites, curtains (draperies in US caving), straws (fine tubular stalactites - 'soda straws' in US), flowstone, gour pools (I think 'rimstone' pools, ditto), cave pearls, helictites (aka 'erratics' but rather unwisely because that is already a definite geological term for a boulder left far from source by a glacier.

They are all of calcite, crystalline calcium carbonate.

Gold is typically not found in limestone caves. Gold is formed through geological processes such as hydrothermal deposition and erosion, while limestone is a sedimentary rock formed from the accumulation of calcium carbonate. However, gold can be found in certain types of geological formations such as quartz veins and placer deposits.

Yarrangobilly Caves were formed by the dissolving of limestone by acidic groundwater over millions of years. The caves contain various formations such as stalactites, stalagmites, and columns created by the deposition of minerals from dripping water. The underground chambers were ultimately carved out by the slow erosion process of water flowing through the limestone bedrock.

Groundwater affects cave formation by dissolving minerals in the rock, creating passageways and chambers. Over time, this process can lead to the formation of stalactites, stalagmites, and other cave formations. Additionally, groundwater can contribute to the erosion of cave walls and ceilings, shaping the overall structure of the cave.

A stalactite is a thin hollow tube that forms when water drips from the cave ceiling through its center, leaving behind mineral deposits that build up over time.

Below the water table is the saturated zone, where the pores in the rock or soil are filled with water. This is where groundwater is stored and flows, providing water for wells and springs. The unsaturated zone above the water table contains both air and water in the pores.

A sea arch forms when the rock of a sea cave is eroded through by wave action, leaving behind a natural arch structure that extends out into the water. Over time, the sea arch may eventually collapse, forming a sea stack.

Formations that grow downward from the top of a cave are called stalactites. Stalactites may be composed of amberat, lava, minerals, mud, peat, pitch, and sand. Formations that grow from the floor upwards are called stalagmites.

(You can remember the difference by thinking of the phrase "ants in your pants". The mites go up and the tights come down.)