Fluvial Landform ( 09.Cave )

                                                                                                                                                      Back to Fluvial Landform

Lava tube,Hawaii.
Lava tube,Hawaii.

  • 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
  • Caves are formed by;

                                 -A combination of chemical processes
                                 -Erosion from water
                                 -Tectonic forces
                                - Microorganisms
                                 -Atmospheric influences
                                - Digging
  • Most caves are formed in limestone by dissolution.
Lechuguilla Cave, New Mexico
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;
                                  -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. 

        Lechuguilla Cave,New Mexico
        Carlsbad Cavern
Large sea cave, Santa Cruz Island, California
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.
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
  • 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

Fluvial Landform (08.Carolina Bay )

                                                                                                                                                      Back to Fluvial Landform

  • Carolina bays are elliptical depressions concentrated along the Atlantic seaboard.
  • Have within coastal ;

                          Delaware                                                            Maryland (Maryland Basins)
                          New Jersey                                                        North Carolina
                          South Carolina                                                   Virginia
                          Georgia                                                               Northcentral Florida
  • Other landform depressions, not widely as Carolina bays.
  • They are found within northern Gulf of Mexico.
  • They are known as  Grady pondsor Citronelle ponds.
  • Carolina bays vary in size from one to several thousand acres.
  •  About 500,000 classic area of the Atlantic Coastal Plain, often in groups.
  • The bays have different vegetative structures.
  • Based on ;

                       depression depth
  • Some bays are open water with large scattered pond cypress.
  • Others are composed of thick, shrubby areas,with vegetation.
  • The southeastern end has a higher rim of white sand.

Common feature of the Gulf of Mexico
  • Un-drained
  • Circular to oval
  • Depressions exhibiting a wide range of area
  • Depth are very coastal plain within Texas & southwest Louisiana
  •  These depressions size from 0.4 -3.6 km in diameter

  • The bays are  rich in biodiversity.
  • Including rare ,endangered species.
  • Species thrive in the bays ,such as;

                                        -wood storks
                                        -migratory waterfowl

  • Mammals such as;

                                     -black bears
  • Other residents;

                        -green anoles
                        -green tree frogs

  • The bays contain trees, such as;

                             -black gum                          -bald cypress
                           -pond cypress                       -sweet bay
                           -loblolly bay                         -red bay
                          -sweet                                    -maple
                         -magnolia                               -pond pine

  • Shrubs such as;

                    -button bush
  • Plants are;
                   -water lilies
                  -various grasses

Fluvial Landform ( 07.Braided Channel )

                                                                                                                                                      Back to Fluvial Landform

  • braided river has a channel.
  • That consists of a network of small channels.
  • Temporary islands called; 

                                                braid bars

  • Braided streams rivers with high slope & large sediment load.
  • That dramatically decrease channel depth &  channel velocity, such as;

                                               River deltas
                                               Alluvial fans

  • Distinct from meandering rivers.
  • Usually highly mobile with river layout.
  • Channels move sideways via differential velocity:

                                        On the outside of a curve, deeper, swift water picks up sediment 
                                        Re-deposited in slow-moving water on the inside of a bend

  • It flow within  valley floor.

Braided channel formation :
  1. an abundant supply of sediment
  2. high stream gradient
  3. rapid and frequent variations in water discharge
  4. erodible banks
  5. a steep channel gradient

  • A stream with cohesive banks.
  • That are resistant to erosion.
  • It will form narrow, deep, meandering channels.
e.g. Brahmaputra-Jamuna River.
       Touat Valley,Africa.

Fluvial Landform ( 06.Bench )

                                                                                                                                                      Back to Fluvial landform

  • bench or benchland is a long.
  • Relatively narrow strip.
  • Gently inclined land.
  • That is bounded by distinctly steeper slopes above and below.
  • Benches have different origins.
  • Created by very different geomorphic processes.

01.The differential erosion of rocks/sediments of varying hardness.
      Resistance to erosion.
      Can create benches.
      Earth scientists called benches "structural benches." 

02. Other benches are narrow fluvial terraces.
       Created by the abandonment of a floodplain by a river/ stream.
       Entrenchment of the river valley.

03.Bench is narrow flat area.
      Seen at the base of a sea cliff.
      Created by waves/ physical ,chemical erosion.
      These benches referred to as;
                                                     coastal benches
                                                     wave-cut benches
                                                     wave-cut platforms

Fluvial Landform ( 05. Bayou )

                                                                                                                                                      Back to Fluvial Landform

  • bayou is body of water.
  • It found in ;

                            1. Flat, low-lying area
                            2.Slow-moving stream /river
                            3.A marshy lake

  • Bayou refer to  changes water level.
  • A bayou is frequently an anabranch or minor braid of a braided channel.
  • That is moving more slowly than the mainstem.
  • Vegetation varies by region,such as;

                                          American alligators
                                          American crocodiles

  • Gulf Coast,United States
  • Mississippi River region
  • Bayou Bartholomew
  • Bayou Lafourche
  • Bayou Teche
  • Cypress Bayou
  • Bayou St. John
  • Big Bayou Canot
  • Buffalo Bayou
  • Bayou La Batre