how does a cave form?

Answer 1

Groundwater dissolves the rock underground. This mainly occurs in carbonates because they are common and easily dissolved.

Answer 2

Extraordinary claims require extraordinary evidence." This dictum from Carl Sagan applies quite well to the recent claim, as chronicled in NOVA's "Mysterious Life of Caves," that microbes feeding on the deadly gas hydrogen sulfide long ago excreted sulfuric acid that helped carve out Lechuguilla, Carlsbad, and other otherworldly caverns. Bacteria dissolving rock? The idea seemed absurd, until geologists and microbiologists working in a still-growing Mexican cave provided the "extraordinary evidence" needed to convince skeptics.

As remarkable as this process is, it is only the most unusual of several principal ways that caves form. Other ways include mildly acidic rainwater eating away limestone caverns, ocean waves scouring out sea caves, and lava forming long tunnels called lava tubes. In this feature, follow along as each of these four agents go about making caves.

Answer 3

Hydraulic pressure on cracks in a cave surface can cause weaknesses in the cliff face. The face of the cliff could be blasted off of the cliff, leaving what will become a cave after being worn down by the waves, through either corrosion or attrition.

Answer 4

water erosion keeps making a tunnel underground bigger as the water works it's way out. then mineral deposits form stalactites& stalagmites and other formations,by soaking thru from the surface.

Answer 5

Caves are formed by geologic processes. These may involve a combination of chemical processes, erosion from water, tectonic forces and atmospheric influences.

Primary caves:

Exploring a lava tube in HawaiiSome caves are formed at the same time as the surrounding rock. These are called primary caves.

Lava tubes are formed through volcanic activity. They are the most common primary caves. Lava flows downhill and the surface cools and solidifies. The lava now flows under this crust, until the eruption ends. If the liquid lava inside the crust flows out, a hollow tube remains.
The most important lava tubes are found on Hawaii (Big Island). Kazumura Cave near Hilo is the longest and deepest lava tube of the world and also the eighth longest cave of the United States.

Blister caves are also formed through volcanic activity.

Painted Cave, one of the world's largest sea caves, Santa Cruz Island, California

Secondary caves:

Secondary caves are formed inside the rock after the rock itself has formed by processes such as solution and erosion.

Sea caves are very common along coasts around the world. Also known as littoral caves, they form from wave action along zones of weakness in sea cliffs. Most commonly these are faults, but may also be dikes or bedding plane contacts. Some wave-cut caves are now high and dry due to uplift. Conversely, in places like Thailand's Phang Nga Bay, solutional caves have been flooded by the sea and are now subject to littoral erosion. Sea caves are generally rather small but may exceed 300 meters in length. One of the largest concentrations of large sea caves is found on Santa Cruz Island in California.

Glacier cave in Big Four Glacier, Big Four Mountain, Washington, ca. 1920.Glacier caves occur in ice and under glaciers, formed by melting. They are also influenced by the very slow flow of the ice which tends to close the caves again. (These are sometimes called ice caves, though this term is properly reserved for caves which contain year-round ice formations).
Solutional caves may form anywhere with rock which is soluble, and are most prevalent in limestone, but can also form in other material, including chalk, dolomite, marble, granite, salt, sandstone, fossilized coral and gypsum. The most common process of cave formation is karstification, which is the solution of rocks by rain water.
Fracture caves are formed when layers of more soluble minerals such as gypsum dissolve out from between layers of less soluble rock. These rocks fracture and collapse in blocks.
Talus caves are the openings between rocks that have fallen down into a pile, often at the bases of cliffs.

Speleothems in Hall of the Mountain Kings, Ogof Craig a Ffynnon, South Wales.The largest and most abundant solutional 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, sinking streams, and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation, including the most common and well-known stalactites and stalagmites. These secondary mineral deposits in caves are called speleothems. The world's most spectacularly decorated cave is generally regarded to be Lechuguilla Cave (New Mexico, USA).

Lechuguilla and nearby Carlsbad Caverns are now believed to be examples of another type of solutional cave. They were formed by acid rising from below, where reservoirs of oil give off sulfurous fumes, rather than by acidic water percolating from the surface.

Answer 6

CAVES ARE FORMED WHEN WATER EATS UP THE ROCK OR MOUTAIN!! SIMPLE ISN'T IT!!

Answer 7

Water is main cause, ie Grand cannon.

Answer 8

http://www.pbs.org/wgbh/nova/caves/form.html

Answer 9

yeah erosion