Land-form Created by river system:
.These are the deep natural underground cave formed by the erosion of rock, especially by the action of water
.These currents erode the river’s bed and create small depressions in it.
.These are drilled into the bed of a river and are cylindrical in nature.
.The diameter and depth varies from few centimeters to meters.
.These are formed due to the whirling impact of the water current in the upper course of the river.
.In India, the potholes can be observed in the river bed of the Kukadi, Krishna and Godavari river in Maharashtra.
A representational picture is given below :
.In mountain ranges, you will find these types of valleys
.V-shaped valleys have steep valley walls with narrow valley floors
.V-Shaped valleys are deep river valleys with steep sides that look like a letter V, a diagram shown below will give you a better understanding
.These are generally formed by the result of erosion and withering by fast flowing rivers and are generally formed in the upper course of the river.
.A deep and narrow valley with steep sides is called a Gorge.
.Many gorge are found in river Ulhas in Thane district in Maharashtra and the gorge of the river Narmada at Bhedaghat near Jabalpur in Madhya Pradesh are well known.
.Waterfalls are formed due to erosion of both hard rock and soft rock.
. As the river flows over the resistant rock, it falls onto the less resistant rock, eroding it and creating a greater height difference between the two rock types, producing the waterfall.
.Over thousands of years, the repeated collapse of the cap rock and retreat of the waterfall produces a gorge of recession.
.Waterfalls exist because of difference in rock types. When a river flows, it passes through many different rock types and when a river passes from a resistant rock bed to a softer one, it erodes softer one very quickly and at the junction between the rock types, it steepen its gradient.
.The highest waterfall in the world is Angel Falls in Venezuela (~800 m).
.The largest waterfall is the Chutes de Khone (Khone Falls) on the Mekong River in Laos.
.The Niagara Falls on the river Niagara and Jog falls in Karnataka on Sharavathi river are famous waterfalls.
Meanders and Ox-bow lakes:
.Meanders are bends in a river that form as a river’s sinuosity increases.
.A meander forms when moving water in a stream erodes the outer banks and widens its valley, and the inner part of the river has less energy and deposits silt.
.Meanders form a snake-like pattern as the river flows across a fairly flat valley floor.
.The sinuosity of a river is a measurement of how much a river varies from a straight line.
.Meanders are formed due to lateral erosion and as the erosion increases over the period of time, the meanders in the river again start flowing in the straight line.
.Meanders formation is a self-intensifying process where a greater curvature results in more erosion of the bank which in turn results in greater curvature.
.Oxbow lakes are an evolution of meanders that undergo extensive deposition and erosion
.When the meanders cut from the main course and water accumulates in this pool then it resembles the shape of the ox bow.
Fan shaped plains:
.These are formed in the region where the Tributaries Rivers joins the main river.
.These are formed due to the deposition of material carried by the Tributaries Rivers.
.These flows come from a single point source at the apex of the fan, and over time move to occupy many positions on the fan surface.
.This deposition resembles the shape a Fan like plains
.These are formed due to the overflows of the river and flood in the nearby areas.
.It is an area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.
.Floodplains are made by downstream travelling meanders.
.Slit carried by the water gets deposited in flooded areas and formed flat plains on both sides of river.
.The Gangetic plain is a flood plain.
.It is an embankment built to prevent the overflow of a river by a ridge of sediment deposited naturally alongside a river by overflowing water.
.When a river floods, it deposits its load over the flood plain due to a dramatic drop in the river’s velocity as friction increases greatly.
.Repeated floods cause the mounds to build up and form levees.
.Delta is a terms coined by Herodotus (The Father of History) after the Greek letter Delta because of the deltoid shaped at the mouth of the Nile river.
.A river delta is a landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or standing water.
.This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot transport away the supplied sediment.
.Over the period of time this deposition builds the characteristic geographic pattern of a river delta.
.Sunderbans delta of the Ganga River is the largest in the world.
Landform created by the actions of River
.A glacier is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its ablation over many years.
.On an average day a glacier moves 1 to 15 meters a day.
.There are two types of glaciers, Continental Glacier and Alpine or Mountain glacier
Landforms Created by Glacier:
.It is half-open steep-sided hollow at the head of a valley or on a mountainside, formed by glacial erosion.
.Cirques are created by glaciers, grinding an existing valley into a rounded shape with steep sides.
.The back wall of the cirque is like a high cliff and the floor is concave and huge in size. The total shape resembles an armchair.
.When a glacier melts completely, water accumulates in the cirque and forms a lake which is known as a tarn.
.U–shaped valleys, or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape, with steep, straight sides and a flat bottom
.As the erosion of the sides is greater than that of the floor, a valley is formed with vertical sides and a wide floor. This valley is called a U-Shaped valley.
.These valleys can be several thousand feet deep and tens of miles long.
.As a glacier moves downhill through a valley, usually with a stream running through it, the shape of the valley is transformed. As the ice melts and retreats, the valley is left with very steep sides and a wide, flat floor. This parabolic shape is caused by glacial erosion striving to decrease friction as much as possible
.It is a valley which is cut across by a deeper valley or a cliff.
.Hanging valleys are often associated with valley glaciers, joining the main valley along its sides.
.Hanging Valley Landforms Have 2 Main Characteristics – a valley that leads to another valley below and A cliff or steep wall below the meeting point
.They are the product of different rates of erosion between the main valley and the valleys that enter it along its sides.
.The tributaries are left high above the main valley, hanging on the edges, their rivers and streams entering the main valley by either a series of small waterfalls or a single impressive fall
.Geologically, a fjord is a long, narrow inlet with steep sides or cliffs, created by glacial erosion
.Fjords are common in Norway, Greenland and New Zealand.
.The material transported and deposited by a glacier is known as moraine.
.a mass of rocks and sediment carried down and deposited by a glacier, typically as ridges at its edges or extremity
.Zigzag hills, with many steeps slopes, made up of long stretches of sand and gravel are called eskers.
.The oval shaped hills of lesser height are called drumlins.
.There are 4 types of moraines – Lateral, Medial, Terminal and Ground