Denudation - class-X

• Water and wind are the main agents of erosion and transportation which erode and carry the loosened material from one place to another
• Eg water - through streams and rivers
• Eg Wind - through dust storms.

Mass wasting, which is sometimes called mass movement or slope movement, is defined as the large movement of rock, soil and debris downward due to the force of gravity. In other words, the earth's outer crust is being 'wasted' away on a 'massive' scale and falling to lower elevations.

The decade between 1930 and 1940, saw long periods of severe droughts accompanied by extreme dust storms in North America 

Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation.

The Narmada river flows through a rift valley and enters the Arabian Sea, forming an estuary rather than a delta. Rivers like the Mahanadi, Krishna, and Godavari flow into the Bay of Bengal and typically form deltas.

• Deposition of materials in lowlands which causes the filling up of the land and its upliftment is called Aggradation. Hence option A is correct.
• Degradation is the lowering of the land.
• Wethering is the breakdown and wearing away of rocks.
• Gradation is the levelling of the land.

Sand dunes are landforms created by the accumulation of sand. In arid regions like western Rajasthan, wind acts as the primary agent, transporting and depositing sand to form dunes.

Barchans are crescent-shaped sand dunes that typically form in areas with limited sand supply and a constant wind direction, which is characteristic of hot desert environments.

Loess is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Winds transport fine particles over long distances and deposit them to form extensive loess plains.

Denudation is the process of lowering and leveling of the earth surface by gradual breaking and wearing away of such earth’s features. The agents which promote these breaking and lowering of the earth’s surface are called the agents of denudation.  Examples of agents of denudation are wind, running water, ice and waves.

Runoff, streams, and rivers carry sediment to the oceans. The sediment in ocean water acts like sandpaper. Over time, they erode the shore. The bigger the waves are and the more sediment they carry the more erosion they cause and form from wave erosion.

Ox bow lake are formed by the erosional work of river.

When weathered particles move down due to gravity alone, the process is called mass movement. Mass movement occur in two ways; it is rapid on sleeper slopes while it is slower on gentle slopes.

Like weathering and mass movements, erosion is also an external process. Erosion occurs through various agents. Wind, running water, glaciers, sea water and groundwater.

When weathered materials move very rapidly and come down the slope it is called rapid mass movement. The main reason of rapid mass movement are:-

• Rockfalls
• Landslides
• Land subsidence

When weathered particles move down due to gravity alone, the process is
called mass movement. Mass movement occur in two ways; it is rapid on
sleeper slopes while it is slower on gentle slopes.

When the weathered materials do not move downward but sink "in situ", this is called slumping. Such rapid mass movements may also occur beccause of earthquakes.

In periglacial regions along the slopes, small layers of soil accumulate because of the movement of soil. This is called solifluction.

When weathered particles move down due to gravity alone, the process is
called mass movement. Mass movement occur in two ways; it is rapid on
sleeper slopes while it is slower on gentle slopes.

Sea caves are coastal landforms created by the erosional power of waves striking against cliffs. The hydraulic action and abrasion of waves carve out cavities in the rock face.

Slumping in simple terms is recurring downward movements of rock debris. Slump is slipping of one or several units of debris with a backward rotation with respect to the slope over which the movement takes place. Thus, it is the process by which the weathered materials do not move downward but sink in situ.

The factors that determine the deposition of sediments are the length of the rivers, volume of water, amount of sediments, and the slope of the river and the earth's surface.

When gravity alone causes rock or sediment to move down a slope, the erosion is called mass movement. This process is also known as mass wasting. It is a process where a mass of rock debris down the slope under the direct influence of gravity. Weathering is not essential for mass movement, though it helps mass movement. Mass movement has two major classes namely:

Solifluction is a process covered under the slow mass movements. It is a process that involves slow downslope flowing of soil mass or fine-grained rock debris saturated or lubricated with water. It is because permafrost (ground that remains completely frozen) is impermeable to water, soil overlying may become oversaturated and slide downslope under the pull of gravity. Thus, in periglacial regions along the slopes, some small layers of soil accumulated because of the movement of the soil are known as solifluction. 

Sea cliffs are usually formed by the process of weathering and erosion. In coastal areas the sea waves erode away the base of the headland. The part of rock that remains form a sea cliff.

A headland is an area of land that extends into a large body of water. It is often a cliff or other elevated landform overlooking a sea or ocean. It is formed when a softer rock in pushed or eroded inwards, the hard rocks sticks out in the sea. 

Landforms like flood levees, flood plains and deltas are formed because of the depositional works of the river.

Sea forms create erosional and depositional landforms. Steep rocky coast rising almost vertically above sea water is called sea cliff which is very precipitous with overhanging crest. Sea canes are formed by the mechanical erosion of rocks by the action of sea. A lagoon is a shallow body of water separated from a larger body of water by barrier islands or reefs. They form in areas with small tidal range.

Lagoons are shallow bodies of water separated from a larger body of water by barrier islands or reefs. In coastal geography, the water trapped between the coast and sand bars is referred to as a lagoon.

Extensive loess deposits are found in northern China, the Great Plains of North America, central Europe, and parts of Russia and Kazakhstan. The thickest loess deposits are near the Missouri River in the U.S. state of Iowa and along the Yellow River in China.

World's largest and fastest growing delta is Sundarban delta.

The Jog Falls on the Sharavati River in Karnataka is widely recognized as one of the highest waterfalls in India.

Barchan dunes are also known as Barkhan. These are crescent-shaped sand dunes which are formed by the action of wind predominately from one direction. In India, Barchans are found in the desert regions of the Rajasthan.

Denudation is the long-term sum of processes that cause the wearing away of the Earth’s surface by moving water, ice, wind and waves, leading to a reduction in elevation and relief of landforms and landscapes. Endogenous processes such as volcanoes, earthquakes, and plate tectonics uplift and expose continental crust to the exogenous processes of weathering, erosion, and mass wasting.

• Denudation is the wearing away of the surface of the earth. It is a larger process which involves the following
  
• 1- Wethering ie breakdown of rocks and other material on earth's surface
• 2- Erosion - removal of materials on the earth's surface from there original place
• 3- Transportation - the movement of eroded material to long distances
• Hence all the options are correct.

• Denudation is the process of wearing away of earth's surface. 
• Wethering is the process of wearing away of rocks on the surface of the earth.
• Thus wethering is the subprocess of denudation. Larger process of wearing away of earth's surface refers to Denudation thus it is the right answer.
• Erosion refers to the removal and movement of the material present on the earth's surface which involves denudation, wethering and transportation, has is not a specific answer.

• Sea-waves continuously strike at the rocks. Cracks develop. Over time they become larger and wider. Thus, hollow like caves are formed on the rocks. They are called sea caves.
•  As these cavities become bigger and bigger only the roof of the caves remains, thus forming sea arches.
•  Further, erosion breaks the roof and only walls are left. These wall-like features are called stacks.
• The steep rocky coast rising almost vertically above seawater is called sea cliff. 

Tapi river does not have a delta at its egress. The Tapi River is also known as the Tapti River. Tapti is the prehistoric Sanskrit name of the river. Tapi is a major River in central India . With a stretch of about 724 km, it is also one of the most crucial rivers in peninsular India.

Currents and Tides is not conducive to the formation of deltas. When a river reaches a lake or the sea the water slows down and loses the power to carry sediment . The sediment is dropped at the mouth of the river. Some rivers drop so much sediment that waves and tides can't carry it all away. It builds up in layers forming a delta.

The Ganges-Brahmaputra Delta also known as the Brahmaputra Delta, the Sunderbans Delta or the Bengal Delta. It is a river delta in the Bengal region of the South Asia, consisting of Bangladesh and the Indian state of West Bengal.

Distributary is called a stream that flows through the deposits of a delta at the mouth of a river. Distributaries are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributary is a tributary.