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The type of climate plays an important role in the formation of plateaus found in various parts of the world. The climatic conditions determine the structure of plateaus. 

Considering the climatic conditions of the world as the basis, the plateaus are classified into the following parts:

1. Humid Plateau 

2. Arid Plateau 

3. Snowy Plateau

1. Humid Plateau: The plateaus with usually 50% humidity and good rainfall are called the Humid Plateaus. In these plateaus, the rivers are fast flowing, narrow and forceful. Thus, humid plateaus are eroded by them. This type of plateau includes Plateau of Cherrapunji, Plateau of Malagasy, Eastern Plateau of Australia, Plateau of Otago in New Zealand.

2. Arid Plateau: These plateaus are formed due to excessive amount of evaporation as compared to the rainfall. Most of the plateaus of this type are found on the Western edges of the continents near the Cancer and Capricorn Lines. This type of plateau includes Plateau of Tarim, Plateau of Potwar, Plateau of Gobi, Plateau of Sedaam.

3. Snowy Plateau: These plateaus are formed in the high latitudes or high regions and most of the part of these plateaus remains covered with snow round the year due to extreme cold. This type of plateau includes Plateau of Greenland, Plateaus of Antarctica and southern part of the plateau of Patagonia.

On the basis of the stage of development, the plateaus are classified into four parts: New Plateau, Mature Plateau, Old Plateau and Rejuvenated Plateau.

On the basis of location, the plateaus are classified into three parts – Intermountain Plateau, Piedmont Plateau and Continental Plateau.

The valleys formed by movements caused due to endogenetic forces come under the category of tectonics. 

This type of valley is classified into two parts: 

1. Synclinal Valley 

2. Rift Valley.

1. Synclinal Valley: Curved folds occurred in rocks due to compression force of tectonic action, which causes anticline and syncline. Synclinal valley is formed in subsided part of the folding. 

2. Rift Valley: Rift Valley is a steep – sided valley formed by the downward displacement of a block of the earth’s surface between two nearly parallel faults. Valley of Narmada River is an example of rift valley.

According to Finch, “Mountains are 600 meters above sea level or higher, and with the slope of 260 degree to 350 degree.”

The plains which are formed from the accumulation of fine soil blown by wind in desert regions are called Loess Plains.

The valleys formed by external erosion forces are classified into the following parts: 

1. River Valley 

2. Glacial Valley 

3. Blind Valley

1. River Valley: River Valley is formed by the vertical and horizontal erosion caused by the flow of rainwater on the earth’s surface. The development of river valley lies on its depth and breadth. The depth and breadth of the valley depend on the surface structure, slope position arid water velocity. The V-shaped valley is formed in the initial stage by river water.

2. Glacial Valley: U – shaped valleys are formed by the process of glaciations. They have a characteristic U shape, with steep, straight sides and a flat or rounded bottom. Glacial valleys are formed when a glacier travels across and down a slope, carving the valley by the action of scouring.

3. Blind Valley: A river flows over a limestone basin until the joints have opened up sufficiently and the stream disappears down a shallow hole. The valley downstream is dry and erosion stops here.

On genetic basis, the valleys are classified into the following types: 

1. Consequent Valley: The valley formed by the initial streams that originate in a particular region in accordance with the initial slope of the land is called Consequent Valley. These valleys develop mainly in newly formed parts, volcanic regions and coastal plains. These valleys develop on the initial surface of elevated terrain in accordance to the slope.

2. Subsequent Valley: The valley formed by streams originated after the consequent stream and joining the master consequent at right angles is called Subsequent Valley. These valleys are found usually in regions with soft rocks.

3. Obsequent Valley: The valley formed by streams flowing in a direction opposite to that of the dip of the rock strata, i.e. opposite to the master consequent stream is called Obsequent Valley. After the formation of subsequent valleys, river tributaries of the river flowing in them are developed.

4. Resequent Valley: The valley formed by streams which flow in the direction of the initial consequent stream but join the subsequent streams, thereby developing in response to a new base level.

5. Insequent Valley: The river valley that remains unaffected by the regional slope and geological structure is called Insequent Valley.

On genetic basis, the valleys are classified into Consequent Valley, Subsequent Valley, Obsequent Valley, Resequent Valley and Insequent Valley.

Continent and ocean are the largest land forms on the earth’s surface. Mountain, plateau and plain are the land forms of the Second Order; and the innumerable land forms formed on them by the external forces are the land forms of the Third Order. None of these land forms are permanent on the earth’s surface.

As a land form develops by endogenetic forces, the process of its destruction begins by exogenetic forces. Tethys Sea was once there, where the Himalayan Mountains stand today. Mountains on getting eroded, transform into the form of plateaus and plains; and the plains, on getting submerged, transform into the form of oceans.

In this way, the cycle of the development of land forms keeps moving continuously. There is enough complexity in the development of land forms. All continents and oceans are made by small and large 20 Tectonic Plates. With the movement of these tectonic plates, tectonic actions take place on their edges, which develop different types of land forms.

The concept of Tectonic Plates has helped in the explanation of occurrences like mountainization, earthquake, volcano and continental drift. In the same way, the concepts of Geomorphic Cycle and Erosion Cycle have paved the way for the understanding of processes related to the development of innumerable land forms of the Third Order.

Highly elevated part above the earth surface having the narrow peak and steep slope, such a land form is called a Mountain. A scholar named Finch defined the mountain as, “Mountains are 600 meters above sea level or higher, and with the slope of 260 degree to 350 degree.”

Mountain – Building Movements: The formation of mountains in the entire world is not a sudden process, but it is the result of a long – term process that took place at different times. Four major mountain – building movements have occurred till now. There has been a long, quiet period between these movements. Compression force must have been stored during the quiet – period, as a result of which, these movements got into action. 

The periods of mountain – building are classified into the following parts:

1. Archean Period 

2. Caledonian Period 

3. Hercynian Period 

4. Alpine Period

1. Archean Period: This event of mountain – building took place about 40 million years ago. This is an event of Cambrian Period. Under this period, the mountains that were formed are Fenno – Scandinavia in Europe; Aravalli Mountain, Dharwad, Chota Nagpur, Cudappah, Mountains of Eastern Ghat in India.

2. Caledonian Period: This period of mountain – building movement took place about 32 million years ago. Due to this movement, there was a lot of change in Europe. Abundant minerals are found in the mountains of this period. The mountains that were formed by this movement are Appalachian in America, Scottish Upland in Europe, Mountains of Ireland, Jura Mountain, Saharai Mountain in Africa, Mozambique Mountain, Mountains of Garhwal, Spiti and Vardhavan Valleys in India.

3. Hercynian Period: This period of mountain-building movement took place about 22 million years ago. Minerals, hydro – electricity and stone for construction are found in abundance in the mountains formed by this movement. The major mountains that were formed by this movement are Tian Shan, Altai Shan, Khingan and Nanshan Mountains of Asia; Eastern Cordillera Mountain in Australia; Mountains of Penine, Harz, Vosges, Black Forest, Bohemia in Europe.

4. Alpine Period: This is the latest period of mountain – building movements, which took place about 3 million years ago. This mountain – building movement was active in the new fold period of Oligocene, Miocene and Paleocene. Due to this movement, new folded mountains were formed. In this, the mountains that were formed are Himalaya, Kunlun, Karakoram, Arakan, Elburz, Hindu Kush, Rockies, Andes, Alps, Balkan, Pyrennes.

The condition of mountains found in any nation or region affects the human activities of that region, their social status, tourism, water availability and religious structure. 

The useful or beneficial effects of mountains on the human life are as follows:

1. Several tourist centers develop in the mountains which promote tourism. 

2. Mountains, provide facilities like recreation, health benefits and adventurous mountaineering. 

3. Mountains determine the natural boundaries. 

4. Mountains play an important role in controlling the climate. 

5. Mountains occupy an important place from security and strategic perspective. 

6. Rivers from the mountains are the source of water for large populations. 

7. Various types of medicinal plants are obtained in mountainous regions. 

8. The dwellers of mountainous regions are adventurous, courageous, hard working, healthy and gentle. 

9. Mountains are important from the religious and spiritual perspective. 

10.Many types of resources are obtained from mountains. 

11.Mountains being peaceful and isolated place, they have been the spiritual center and land of penance for the sages since the ancient period. 

12.Many holy pilgrim destinations are developed in the mountains.

The height of mountains is not found similar in the entire world. Considering the height of mountains as the basis, 

The mountains are classified into the following types: 

1. High Mountains 

2. Average High Mountains 

3. Less High Mountains 

4. Low Mountains

1. High Mountains: The mountains whose height is more than 6000 feet or more than 2000 meters are called High Mountains. 

2. Average High Mountains: The mountains whose height ranges between 4500 feet to 6000 feet or between 1500 meters to 2000 meters are called Average High Mountains. 

3. Less High Mountains: The mountains whose height ranges between 3000 feet to 4500 feet or 1000 meters to 1500 meters are called the Less High Mountains. 

4. Low Mountains: The mountains whose height ranges between 2000 feet to 3000 feet or between 700 meters to 1000 meters are called Low Mountains.

A steep – sided valley formed by the downward displacement of a block of the earth’s surface between nearly parallel faults is called the Rift Vallay.

Valley is generally considered to be an unassertive topography of river. The formation of valleys also occurs due to diastrophism. Valleys are also formed by underground water and glaciers. Valley is basically an elongated depression on the earth’s surface, usually between the ranges of hills or mountains which is created by tectonic events or external forces. Valley presents various forms from its stage of development to its last stage.

The plateau whose most of the part remains covered with snow round the year due to extreme cold is called a Snowy Plateau.

The mountains whose height is more than 6000 feet or more than 2000 meters are called High Mountains.

When the flowing rivers carry away the eroded debris from the high parts and their deposition is made in the lower parts of mountains, then the plains formed by this action are called Piedmont Plains.

The major mountains which were formed in the Alpine Mountain Period are Himalayas, Arakan Yoma, Elburz, Hindu Kush, Rockies, Andes, Alps, Balkan and Pyrennes.

When the intermediate part between two parallel cracks is elevated upwards or both the two sides of the middle part are stuck downwards, then the mountain formed by this process is called Block or Faulted Mountain.

(b) Continent and Ocean

Correct Answer is : (d) Erosion

Plateau which is located in the foothills of the mountains having the mountain at one of its side and the sea or plain at the other side is called the Piedmont Plateau.

Due to the process of compression, when the rocks take the curved form, then a downward and U – shaped fold in the layers of rocks in the earth’s surface is called the Syncline.

On the basis of age, the mountains are classified into the four mountain building periods : Archean Mountain Period, Caledonian Mountain Period, Hercynian Mountain Period and Alpine Mountain Period.

Mountains are classified on the basis of their formation process, their height, age, location, structure and texture.

On the basis of height, mountains are classified into four parts – High Mountains, Average High Mountains, Less High Mountains and Low Mountains.

Himalaya, Ural and Andes, etc. are the fold mountains which are the new mountains of the world.

The major Accumulated Mountains of the world include Fujiyama Mountain of Japan, Vesuvius Mountain of Italy and Kilimanjaro Mountain of Africa.

(c) Cherrapunji Plateau

Mountains which are formed by the collected debris and deposited substances accumulated in the form of large piles by air, river, glacier, waves and volcano.

Residual Mountains are the remnants of old mountains which have been worn down by agents of denudation. They are usually hard resistant rocks that are left standing after the surrounding areas have been reduced by agents of denudation.

 About 22 million years ago, folded mountain building collisions are known by the names Hercynian, Variscan and Armorican. Altai, Khingan, Nanshan, Eastern Cordillera Mountains of Australia, and Panine and Harz Mountains in Europe are formed from them.

Narmada river flows from east to west through the Rift valley formed by the process of faulting.

Plateaus which are formed by the erosion caused by glaciers in high latitudes or high relief regions are called the Glacial Plateaus. This type of plateau includes Plateau of Garhwal, Plateau of Labrador, Plateau of Scandinavia, Plateau of Alaska, Plateau of Antarctica, South – Eastern Plateau of Africa, Prussian Plateau in Germany, Gulmarg Plateau in Kashmir.

In the valley developed before the uplift of a landmass, even after the uplift of the land, the river flows in pre – built valley, then it is called the Ansequent Valley. These valleys are formed when the preceding stream retains its surface even on the uplifting of landmass.

Consequent Valley: The valley formed by the initial streams that originate in a particular region in accordance with the initial slope of the land.

(b) Tibetan Plateau

The valley formed by streams originated after the consequent stream and joining the master consequent at right angles.

In these plateaus with rough and uneven terrain, the ridges are of steep slope. Their sharp peaks expand more. Such plateaus are called the Mature Plateaus. The structure of these plateaus varies in arid and humid regions. The edges of these plateaus generally look like stairs. Appalation Plateau is an example of this type of plateau.

When the plateau is surrounded by mountains from four or two sides, then due to being located between the mountains, it is called the Inter – mountain Plateau. These plateaus are formed with the formation of fold mountains by endogenetic force. This plateau is originated mainly in the form of a central body. In these plateaus, the main examples are Tibetan plateau between Himalaya and Kunlun mountains, Sedaam plateau between Kunlun and Nanshan mountains, Iran plateau between Elburz and Zagros mountains, Anatolia plateau between Pontik and Taurus mountains.

The concept of Plate Tectonics has helped in explaining the processes like mountainization, earthquake, volcano and Continental Drift.

Elevated part above the earth surface, whose top surface is flat and broad, and the edges are with steep slope, is called the Plateau.

The plateau which is formed when the lava erupted from the volcanic activity extends over a large area, and over the period of time, it cools downs and solidifies, is called the Lava – Made Plateau.

Plateaus which attain the old stage are re-elevated due to the internal movements and process of erosion re – starts on them, then such plateaus are called Rejuvenated Plateaus.

The formation of mountains is not a sudden process, but the mountains are formed as a result of a long process. This formation of mountains occurred in various mountain – building periods. 

There are four periods of mountain – building on the earth’s surface:

1. Archean Mountain Period: This mountain – building movement occurred about 40 million years ago in Cambrian period. 

2. Caledonian Mountain Period: This, movement occurred about 32 million years ago. 

3. Hercynian Mountain Period: This movement occurred about 22 million years ago. 

4. Alpine Mountain Period: This movement occurred about 3 million years ago.

On the basis of origin, the plateaus are classified into four parts – Lava – Made Plateau, Glacial Plateau, Air – Made Plateau and Water – Made Plateau.

The rock particles which are soft and broken by mechanical weathering are blown away by the wind. This wind causes the abrasion of the elevated rocks coming in its path. The plains formed by this action are called the Pediplain.

The importance of plateaus is significant, which is being explained by the following points: 

1. Fertile soil is found on the plateaus which is useful for intensive agriculture. 

2. Plateaus are the store – house of many precious minerals. 

3. Water – reservoirs are built on their hard surface. 

4. Waterfalls are formed by the rivers descending from the steep slopes of the plateaus. 

5. The means of transportation are more developed on the plateaus than the mountains. 

6. Plateaus are more populated than the mountains.

The plateaus which extend over the entire part of a country or continent are called Continental Plateaus.