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Deposition occurs when the speed of wind is reduced by the presence of obstacles like bushes, forests and rock structures. The sediments carried by wind get deposited on both the wind ward and leeward sides of these obstacles. Some of the depositional landforms are sand dunes, barchans and loess.

Sand Dune: In deserts, during sandstorms, wind carries loads of sand. When the speed of wind decreases, huge amount of sand gets deposited. These mounds or hills of sand are called sand dunes. There are different types of sand dunes.

Barchan: Barchans are isolated, crescent shaped sand dunes. They have gentle slopes on the windward side and steep slopes on the leeward side. Transverse 

Dunes: Transverse dunes are asymmetrical in shape. They are formed by alternate slow and fast winds that blow from the same direction.

Longitudinal Dunes: Longitudinal dunes are long narrow ridges of sand, which extend in a direction parallel to the prevailing winds. These dunes are called Selfs in Sahara.

Loess: The term loess refers to the deposits of fine silt and porous sand over a vast region. Extensive loess deposits are found in Northern and Western China, the Pampas of Argentina, in Ukraine and in the Mississippi Valley of the United States.

A Glacier is a large mass of ice that moves slowly over the land, from its place of accumulation. It is also known as ‘River of ice’. The place of accumulation is called snowfield. The height above which there is a permanent snow cover in the higher altitude or latitude is called snowline. Higher the latitude, lower the snowline from sea level.

The gradual transformation of snow into granular ice is called ‘firn’ or ‘ neve’ and finally it becomes solid glacial ice. 

Movement of Glacier: The large mass of ice creates pressure at its bottom and generates heat. Due to this, the glacier melts a little and starts to move The rate of movement of a glacier varies from a few centimetres to several hundred meters a day. The movement of glaciers depends on slope, volume of the glacier, thickness, roughness at the bottom (friction) etc., and Temperature. Like the rivers, glaciers also carry out erosion, transportation and deposition.

Types of Glacier: Glaciers are broadly divided into two types based on the place of occurrence, such as Continental glacier and valley glacier.

(c) tectonics

In the ancient period, Gondwana land moved towards north direction.

cirque is not a depositional feature of a glacier.

(d)  is true

By the constant wearing down action of wind, the bottom gets eroded away to form a mushroom like structure. So the Pedestal rock looks like mushroom.

1. SIAL consists of Silica and Aluminium. 

2. SIMA contains Silica and Magnesium. 

3. SIAL is lighter than SIMA. Therefore SIAL floats over SIMA.

• The Pacific Ring of fire is an arc around the Pacific Ocean where many volcanoes are found. 
• The Pacific Ring of fire is the most seismically and volcanically active zone in the world.

The ‘Pedosphere’ is part of the lithosphere made up of soil and dirt. It exists at the interface of lithosphere, atmosphere, hydrosphere and biosphere.

Folding:

Due to lateral compressional forces, the plates are forced to move upwards and downwards. This is called‘ Folding’.

Faulting: 

The movement of plates also create stress and tension in the rocks, causing them to stretch and crack. This called ‘faulting’.

(b) The Ganga – Brahmaputra Delta

1. The tectonic plates float independently. 

2. Collisions of the tectonic plates produce mountain ranges and other irregular surface features both on land and the ocean floor. This phenomenon is called ‘Plate tectonics.’

• Seismic activity 
• Earth’s magnetism 
• Volcanoes
•  Mined rocks 
• Gravitational force 
• Meteors

• Seismic Activity: Frequency and size of earthquake. Earth’s magnetism: Due to the movement of molten material under the earth’s crust. 
• Volcanoes: A rupture in the crust of a planetary mass object such as Earth, that allows hot lava, volcanic ash & gases to escape. 
• Mined Rocks: Excavating hard minerals 
• Gravitational force: A natural phenomenon. 
• Meteors: A bright streak of light.

The Pacific Ring of fire is an arc around the Pacific Ocean. It is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and plate movements. It has 452 volcanoes (more than 75% of the world’s active and dormant volcanoes). The Ring of Fire is a direct result of plate tectonics: the movement and collisions of lithospheric plates. That is why it is the most seismically and volcanically active zone in the world.

(a) Pot holes

Earthquakes are generally caused by the sudden vibrations in the Earth’s crust which spreads outward in all directions as waves from the source of disturbance.

(a) epicentre

GPS works by sending radio signals from satellites to ground stations. The distance between the satellites and station is recorded. Over time, these distances change slightly. Scientists can measure the rate of Tectonic Plate movements by recording the time it takes for ground stations to move a given distance.

(a) P – waves

This generally originate from mountains river

(i) (ii) are false (iii) true

(d) Thermal energy

The movement of tectonic plates is induced by thermal energy

The process of dissolution of rock substances in water is solution.

The boundary that separates the Mantle from the. core is called ‘gutenberg Discontinuity’.

Igneous rocks are formed by the cooling of molten matter of the earth.

Glaciers are slowly moving. compacted masses of ice and snow found in the high mountains and polar regions. 

There are two types of glaciers, they are: 

• Continental glaciers 
• Mountain or Alpine or valley glaciers.

(a) Carbonation 

(b) Plateau

(c) Gradation 

(d) The snowline

On the basis of mode of formation, rocks are classified into three types. Thy are: 

• Igneous rocks 
• Sedimentary rocks 
• Metamorphic rocks.