Fluvial Landform ( 09.Cave )

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Lava tube,Hawaii.

• A cave/cavern is a natural underground space.
• It is large enough for a human to enter.
• Caves form naturally by the weathering of rock extend deep underground.
• Cave refer to,such as;

                                       -sea caves

                                      -rock shelters

                                      -grottos.

• Caves are formed by;

                                 -A combination of chemical processes

                                 -Erosion from water

                                 -Tectonic forces

                                - Microorganisms

                                 -Pressure

                                 -Atmospheric influences

                                - Digging

• Most caves are formed in limestone by dissolution.

                 

Lechuguilla Cave, New Mexico

solutional caves

• Frequently occurring caves.
• Formed in rock.
• Soluble as;

                                              limestone                         chalk

                                             dolomite                            marble

                                              salt                                    gypsum

• Rock is dissolved by natural acid in groundwater.
• The largest & abundant solutional caves located in limestone.
• Limestone dissolves under the action of;

                                  -rainwater
                                  -groundwater charged with H₂CO₃ (carbonic acid)
                                  -naturally occurring organic acids

• The dissolution process  landform known as karst.
• characterized by sinkholes.
• Limestone caves are adorned with calcium carbonate.
• Slow precipitation. 

e.g.

        Lechuguilla Cave,New Mexico

        Carlsbad Cavern

Large sea cave, Santa Cruz Island, California

Primary caves

• Lava tubes formed volcanic activity.
• Lava flows downhill.
• The surface cools and solidifies.
• The hotter lava continues to flow under that crust.
• The liquid lava beneath the crust flows out, a hollow tube remains, thus forming a cavity.
•  Examples

                           Canary Islands, Hawaii

                           Kazumura Cave,Hilo

• Other caves formed through volcanic activity include;

                               -rift caves

                              -lava mold caves

                             -open vertical volcanic conduits

                             -inflationary caves

Ogof Craig a Ffynnon, South Wales.

Sea caves

• Found along coasts.
• Littoral caves formed by wave action.
• Some wave-cut caves are above sea level .
• In places such as;

                                   -Thailand's Phang Nga Bay

Erosional caves

• Formed by erosion.
• These can form in any type of rock.
• There must be some zone of weakness to guide the water,as a fault,joint.
• A sub type of the erosional cave is the wind/aeolian cave.

Fracture cave

• Glacier caves occur in ice & under glaciers.
• Formed by melting.
• Influenced by very slow flow of the ice.
• These are called ice caves.

Fracture caves

• Formed by layers of more soluble minerals.
• Dissolve out from between layers of less soluble rock.
• These rocks fracture & collapse in blocks of stone.

Talus caves 

• It called as talus.
• Openings between rocks.
• That fallen down into a pile at the bases of cliffs.

Anchialine caves 

• Usually in coastal areas.
• Containing a mixture of freshwater & saline water.
• Contain highly specialized and endemic fauna.

Branchwork caves

• They are made up of passages.
• That join downstream as tributaries.
• Formed near sinkholes 
• Converges into other higher order branches downstream.

Angular Network caves

• Formed by intersecting fissures of carbonate rock.
• that have fractures widened by chemical erosion.
• These fractures form high, narrow, straight passages.
• That persist in widespread closed loops.

Anastomotic caves

• Largely resemble surface braided streams.
• Their passages separating.
• They usually form one bed/ structure.
• Only rarely cross into upper or lower beds.

Spongework caves

• Formed by solution cavities are joined by mixing of chemically diverse water.
• The cavities form a pattern.
• That is three-dimensional & random, resembling a sponge.

Ramiform caves

• Form as ;

                        irregular large rooms

                        galleries

                        passages

• These randomized three-dimensional rooms
• Form from a rising water table.
• Erodes the carbonate rock with hydrogen-sulfide enriched water.

Pit caves 

• Called as;

                       vertical caves

                       potholes cave

• Consist of a vertical shaft
• They may or may not be associated with one of the above structural patterns.

World's five longest surveyed caves

1. Mammoth Cave, Kentucky, USA
2. Sistema Sac Actun/Sistema Dos Ojos, Mexico
3. Jewel Cave, South Dakota, USA
4. Sistema Ox Bel Ha, Mexico
5. Optymistychna Cave, Ukraine