Fluvial Landform ( 05. Bayou )

                                                                                                                                                      Back to Fluvial Landform

• A bayou is body of water.

• It found in ;

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

• 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;

                                          Crawfish
                                          Shrimp
                                          Shellfish
                                          Catfish
                                          Frogs
                                          Toads
                                          American alligators
                                          American crocodiles
                                          Myriad 

e.g.

• 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

Fluvial Landform ( 04. Arroyo )

                                                                                                                                                      Back to Fluvial Landform 

arroyo in the Gobi Desert, Mongolia.

• An arroyo  called as;

                                         Brook
                                         Wash
                                         Wadi (Africa)
                                         Rambla (Spain)

• It is usually;

                             dry creek 
                             stream bed—gulch

• That temporarily or seasonally fills.

• It flows after sufficient rain.

• Arroyos are natural fluvial landforms.

• It constructed flood control channels. 

• Arroyos are principal transportation routes & recreational locations.

• A shallow water table lowered in desert arroyo valleys can reduce saline seeping .

•  Natural arroyos are made the process of arroyo-cutting.

• In agriculture areas farmers traditionally relied on small constructed arroyos.

• An example of larger constructed arroyos is in Albuquerque, New Mexico.

examples

 Southern California

Arroyo Seco

Los Angeles River

Las Cruces Arroyo North Fork

Fluvial Landform (03 Anabranch )

                                                                                                                                                      Back to Fluvial Landform

Anabranches at the junction of the Yukon River & Koyukuk River,Alaska

• An anabranch is a section of a river/ stream.

• That diverts from main channel /stem of the watercourse.

• Local anabranches result of small islands in the watercourse.

• In larger anabranches, diverge for a distance of several km before rejoining the main channel.

• Anabranching river is a river with many anabranches.

• An anastomosing river is an organic-rich subset of this river type.

• A bayou is also anabranch.

e.g.

• Fraser River delta,ritish Columbia, Canada
• North Arm Fraser River
• Middle Arm Fraser River
• South Arm Fraser River

Fluvial Landform ( 02.Alluvial Fan )

                                                                                                                                                      Back to Fluvial Landform 

Alluvial fan, French Pyrenees

• An alluvial fan is a fan/cone shaped landform.

• Deposit of sediment crossed & built up by streams.

• Debris flows called a debris cone /colluvial fan.

• These flows come from a single point.

• Source at the apex of the fan.

• Fans are  found in canyon draining from mountainous terrain.

• It emerges out onto a flatter plain.

• Alluvial fans into a single apron is called a bajada(compound alluvial fan)

• Alluvial fans are  found in desert areas.

• Periodic flash floods from nearby thunderstorms in local hills.

• The watercourse in an arid climate has leading to a narrow defile.

• Phreatophytes are plants concentrated at the base of alluvial fans.

• Alluvial fans also develop in wetter climates.

• Alluvial fans are subject to flooding.

Fluvial Landform (01. Ait )

                                                                                                                                                      Back to Fluvial Landform

Bush Ait on the River Thames,Berkshire

• An ait called as eyot.

• It is a small island.

• It is especially used to river islands.

• It found on the River Thames.

• Its tributaries in England.

• Aits are  formed by;

                             -Deposition of sediment in the water.

                             -Accumulates over a period of time.

• An ait is  long & narrow.

• It is a permanent island.

• Aits  also be eroded.

• The resulting that;

                              -sediment is deposited  downstream

                              -create another ait

• A channel with numerous aits is called a braided channel.

Erosion Landform (26. Valley )

                                                                                                                                                      Back to Erosion Landform 

Bridal Veil Falls,Yosemite National Park

• A valley called as dale.

• A very deep river valley called a canyon/ gorge.

• U-shaped / V-shaped are formation of valleys.

• Through the valley which a river runs.

• A small, secluded wooded valley known as;

                   a dell 

                   a glen (Scotland)

• A wide, flat valley is known as strath.

• A mountain cove is a small valley.

• Which  results from  erosion of a geologic window.

• A small valley surrounded by mountains/ ridges.

• It is sometimes known as a hollow.

Death Valley in bloom.

•  A deep, narrow valley is known as a coon.Such as;

                                        canyons

                                        ravines

                                        gorges

                                        gullies

                                        kloofs

• The exact shape depend on stream flowing through it.

• Rivers with steep gradients produce steep walls.

• Shallower slopes produce broader & gentler valleys.

• Some broad V examples ;

                                            Black Canyon of the Gunnison National Park
                                            Grand Canyon NP
                                            Inn valley 

• First human complex societies originated in river valleys.

                           e.g.    Nile                                          Tigris-Euphrates

                                     Indus                                       Ganges

                                    Yangtze                                    Huang He

                                    Mississippi                               Amazon

• A vale is a wide river valley.

• usually with wide flood plain / flat valley bottom.

• Vales commonly occur between  escarpment slopes of pairs of chalk downs.

U-shaped valley

U-shaped valley in Glacier National Park in Montana, United States.

• Carved by glaciers.

• It is normally U-shaped. 

• Often littered with small boulders.

• That were transported ice.

• Floor gradient doesn't affect valley's shape.

• Continuously flowing glaciers(ice age) & large-sized glaciers carve wide, deep incised valleys.

Carved valleys:

• Yosemite Valley
• Side valleys
• St. Mary River,Glacier National Park,Montana, USA.

Tunnel valley

• A tunnel valley is 

                                       Large

                                       Long

                                       U-shaped

• Originally cut under the glacial ice.

•  It is near the margin of continental ice sheets.

• Long: up to 100 km

• Wide: 4 km 

• Deep: 400 m 

• Formed by sub glacial erosion by water.

• Served as sub glacial drainage pathways.

• It carrying large volumes of melt water. 

• Their cross-sections exhibit steep-sided flanks similar to fjord walls, and their flat bottoms are typical of subglacial glacial erosion.

Hanging valleys

• A hanging valley is a tributary valley.

• The floor at a higher relief .

• They have U-shaped valleys.

• Waterfalls form at or near the outlet of the upper valley.

• Hanging valleys are product of varying rates of erosion of the main valley.

Hollow Valley

• It is a small valley/dry stream bed. 

• Formed by river valleys.

• e.g.Mansfield Hollow

e.g

• Aburra Valley (Colombia)
• Barossa Valley (Australia)
• Cauca Valley (Colombia)
• Central Valley (California) (California, United States)
• Danube Valley (Eastern Europe)
• Death Valley (California, United States)

Erosion Landform ( 25. Tepui )

                                                                                                                                                      Back to Erosion Landform 

Autama tepui

• A tepui is a table top mountain /mesa.

• Found in the Guiana Highlands,South America

                                 Venezuela

• Tepui means "house of the gods".

• Found as isolated entities.

• Unique array of endemic plant & animal species live there.

• Most outstanding tepuis are;

                                                       Neblina

                                                       Autana

                                                       Auyantepui

                                                       Mount Roraima

• They are composed of sheer blocks of Precambrian quartz arenite sandstone.

• That rise from the jungle.

• It gives spectacular natural scenery. 

• Auyantepui is the source of Angel Falls, the world's tallest waterfall.

Kukenan tepui

• These are the remains large sandstone plateau.

• That covered the granite basement.

• Range in elevation from 1,000 - 3,000 m.

• The Gran Sabana is the highest tepuis.

• On top of the mountains grow;

                                                 various types of forests.

                                                 wide variety of orchid

                                                 bromeliad

                                                 carnivorous plant

tepui mountins venzuela

• Tepuis exhibit surface features & subsurface caves.

• Karst topography formed in more water-soluble rocks.

• Caves include the Abismo Guy Collet. (671m deep ) 

• The deepest quartzite cave in the world.

• The mesas are pocked with giant sinkholes up to 300 m.

• These sinkholes are formed the roofs of tunnels carved by underground rivers collapse.

Sinkhole

• The tepuis known as  islands above the rainforest.

• A few of mountains are cloaked by thick clouds almost the whole year.

• Notable  tepuis

• Auyantepui

                            The largest 

                            Surface area of 700 km².

                           Angel Falls drops from a cleft in the summit.

• Mount Roraima

                            The borders of Venezuela, Brazil,  Guyana meet on the top.

• Matawi Tepui

                              Known as Kukenán.
                              It is the source of the Kukenán River.

                              Considered the "place of the dead".

                               Located next to Mount Roraima in Venezuela.

• Autana Tepui 

                             1,300 m above the forest floor. 

                            A unique cave runs from one side of the mountain to the other.

• Ptari Tepui's 

                         Sheer rock walls are so isolated.

                         High number of endemic plant & animal species found there.

• Sarisariñama Tepui

                          Famous for circular sinkholes.

                          Which go straight down from the mountain top.

                          The largest sinkhole is 350 m in diameter.

                          They harbor an ecosystem composed.

                           Unique plant & animal species lives at the bottom .

• Endemic fauna & flora represent of ancient species was an inspiration to the novel The Lost World by Arthur Conan Doyle.

• Much of the story of Pixar--Disney 2009 film Up takes place among the tepuis. 

• The film includes numerous rock formations & an Angel Falls-like waterfall called "Paradise Falls".

venezuela tepui

The steep rock wall of Mount Roraima.