Define Weathering?
- Weathering is breaking up of rocks on the earth surface.
- Weathering is caused by heat, cold, frost, chemical reactions, plants and animals.
Define Erosion?
Erosion is wearing away of landforms by different agents like running water, wind, glaciers.
How Erosion is slowed down?
- It is slowed down by Plants.
- Plants root tighten the rock particles and prevent them from eroding.
- Plants are the natural barrier for flowing water and winds.
- Most powerful agent of erosion is running water.
Few important key terms:
- Source – The place where river originates.
- Mouth – The place where river joins another body.
- River basin – The area which is drained by river and it’s tributaries.
- Delta – A depositional landform created near the mouth of the river.
How running water carries its work of erosion?
- The eroded material is transported by running water.
- It erodes the rock over which it flows.
- The transporter material is also deposited by it.
How are V shaped valleys formed?
- In hilly regions, due to the steep slope of land, the river carries small volume of water.
- Due to the narrow stream it flows rapidly with enormous erosive power and forms landforms.
- The most common landform is V shape the valley.
How I shape valley are formed?
- It is formed when river erodes vertically through hard rocks.
- Example George – very deep and narrow valley.
How waterfalls are formed?
- Waterfall is formed when the water of the river falls almost vertically down a steep valley side.
- It is caused mainly by
- Sudden break in landform due to faulting.
- Sudden drop of the slope of the river bed.
- Example Victoria Falls on river Zambezi.
- Angel falls in Venezula South America.
- Jog falls in Karnataka, India.
What does a rapid in waterfall?
Rapid is term given to steep sloping segment of swift flowing river.
Define Meanders?
Loop and large bends in river due to erosion is termed as Meanders.
How Oxbow lakes are formed?
- Due to continuous erosion and deposition meander loops are almost circular and come very close together.
- Over the period of time, strip of land is cut by river in two loop taking a straight course.
- Circular loop is completely cut off from the main channel and result in the formation of the Oxbow lakes.
What are Natural leeves?
- Alluvial soil are abundantly deposited near the river channels.
- After many floods these deposit pile up along banks of the river and form raised embankments called as Natural leeves.
What are Distributaries?
The main channel of river is divided into several channel called as Distributaries.
Write short note about Delta?
- A Delta is the depositional landform formed by many distributaries generally due to deposition of the sediment by respective river.
- The shape of the delta is Triangular.
- Ganga Brahmaputra Delta is the largest delta in the world.
- Major Indian rivers that drain into Bay of Bengal form delta at their mouth (of the river).
- Rivers that drain into the Arabian Sea do not form deltas, because they are short and cannot accumulate much sediments.
Write short note on Marine deposition or Marine erosion?
- Hard rocks in the sea are eroded by the action of the sea waves.
- These rock material are carried by receding waves.
- Rock material present in the sea water causes the erosion of landform against which it crashes.
- This is known as Marine deposition or Marine erosion.
How are Sea Cliffs formed?
- When waves crash against high rocky Coast near the base Sea Cliffs are formed.
- The rocks near the base or eroded.
- Over a period of time the rocks are hollowed apart and collapse.
- It leaves the steep wall of rock facing the sea.
- These are called as Sea Cliffs.
How Sea Arch are formed?
- When the headland projecting into the sea is dashed by sea waves a passage is created.
- This passage is called as Sea Arch.
How Stacks are formed?
When the roof of the arch is eroded, it collapses and these are termed as stacks.
What is a Lagoon?
- Lagoon is partially enclosed lake. when seawater is trapped between sandbars and the coast, lagoons are created.
- Example: Chilka Lake in Odisha is the largest lagoon in India.
Define Glacier and its function?
- Glacier is river of snow and ice that moves out slowly from snow field. [Snow falling in high latitudes and heights].
- Glaciers move few metres a day.
- Main work of the glaciers transportation, erosion and deposition.
How U shaped valleys are created?
- When Glacier passes through the valley, floor and sides of the valley are eroded by rock pieces in glacier.
- So the floor becomes flat and sides becomes steep resulting in U shaped valley.
What is Cirque?
Glaciers carves deep hollows along slope of the mountain. This develope into armchair like depression known as Cirque.
What is Tarn?
When glaciers melt, the circular depression is filled with water and forms the lake called as Tarn.
How Glaciers moraines are formed?
When Glacier start melting its capacity to carry the load is reduced and hence it deposits the rock material on floor and side of valley. These deposits form Glacial moraines.
Why wind is a major agent of erosion in deserts?
- Windows also erodes, transport and deposit rock materials.
- It is an effective agent of erosion in desert due to the absence of vegetation.
- Strong winds erode the rocks and carry large amount of the sand, dust particles and gravels.
How Mushroom Rocks are formed?
- The wind usually erodes the lower part of the rocks than the upper part.
- It gives rock mushroom shape appeareance. So it is called as Mushroom rocks.
What are Sand Dunes?
- Sand Dunes are coarse particles deposited in the form of hillocks.
- They are developed when their path is blocked or obstructed.
- They vary in height from few metres to 300 metres.
- Leeward slope is steep and windward slope is gentle.
- Sand dunes are mostly formed in groups.
What are Loess?
Sometimes fine dust particles are carried by wind and deposited in distinct region.
These deposit developing into thick layer of soil, these deposits are called as Loess.
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