UPSC Geography Interior of the Earth / पृथ्वी का आंतरिक भाग Short Notes - Geographical Features

Geographical Features

• Geographical features   are   the components of the Earth.
• Landform: Land forms are the recognizable unit of natural features on the earth's surface with varying shape, size and structure. It could be mountains, plateaus, valleys or small features like hills, eskers or canyons.
• Landscape: Large track of earth's surface or many related landforms with an aesthetic appeal together make up landscape.
• Topography: The arrangement of natural or artificial physical features of an area on the earth's surface, their inter relationship and configuration of structural entity is known as topography.
• Terrain: It   is   the   physical characteristics of natural feature of an area, i.e. its landforms, vegetation and soils.

Classification of Landforms

Mountains: It is a naturally uplifted portion of earth's surface from its surroundings.

1. Fold Mountains: Folded mountains were developed due to the tectonic activities where the upper part of the earth's crust are folded and warped toproduce rocky outcrops, hills or mountain. Alps in Europe, Rockies of North America, Andes of South America, Himalayas of Asia and Atlantic of North Africa.
2. Block Mountains: Block mountains have developed due to swelling of earth's crust bound by tectonic fault and characterised by massiveness, stup slopes, and comparatively smooth topography. Varger in France, Black forest mountains in Germany and Salt Range in Pakistan.
3. Volcanic Mountains:   Mountain formed due to the accumulation of molten lava flowing out from a volcanic eruption. Hence they are generally cone shaped mountains with a depression at the top. Mount Mauna Loa in Hawai Islands, Fuji Yoma of Japan and Mount Popa in Central Myanmar.
4. Residual or Dissected Mountains: Nilgiris, Parasnath, Girnar and Rajmahal.

Plateau

• Plateaus are extensive area characterized by flat and rough top surface, steep sidewalls which rise above the neighbouring ground surface at least for 300 metres.
• Causes about 33% of the total earth's area.

Classification of plateau

1. Plateau formed by exogenetic processes. These are-

(i)      Glacial Plateau, e.g. Garhwal plateau, Greenland, Antarctica.

(ii)    Fluvial Plateau, e.g. Kaimur plateau,  Bhander plateau, Rewa Plateau, Rohtas Plateau.

(iii)    Aeolian Plateau, e.g. Porwar Plateau (Pak), Loess plateau (China).

2. Plateau formed by endogenetic processes. These are-

(i) Intermontane Plateau: The plateaus v/hich are parlly or fully enclosed by mountains are known as intermontane plateaus.  These  are the results of the mountain- building process which was accompanied by a vertical uplift   of  tlie   adjoining enclosed lands, e.g. Tibetan plateau,  Bolivian  plateau, Peruvien plateau, Columbian plateau and Mexican plateau.

(ii) Piedmont Plateau : It is situated at the foot of a mountain, it is bounded on the opposite sides by a plain or an ocean. It is also called the plateau of denudation because areas which were formerly high have now been reduced in elevation by various agents of erosion, e.g. Appalachian plateau, Patagonien plateau (Argentina).

(iii) Dome Plateau : It is formed when land mass is uplifted, e.g. Ozark Plateau (USA), Chota- nagapur plateau (Jharkhand).

(iv) Lava Plateau : It is formed due to accumulation of thick layers of basaltic lava, e.g.

Columbia   plateau   (USA), Mahabaleshwar     plateau, Panchgani tableland.

(v) Continental Plateau : They rise   abruptly   from   the lowlands or from the sea, e.g. Deccan plateau of India, Ranchi   plateau,   Shillong plateau, Columbia plateau [USA), Mexican plateau. etc.

(vi) Coastal Plateau: Example- Coromandel coastal upland of India.

(vii) Desert PIateau: Example- Arabian Plateau.

(viii) Humid Plateau: Example- Shillong Plateau, Assam Plateau, Mahabaleshwar Plateau etc.

(ix)Young Plateau:  Example- Idaho Plateau (USA), Colorado Plateau (USA), Mahabaleshwar

Plateau,   Khandala   Upland [Maharashtra).

(x) Mature Plateau: Example- Ranchi Plateau, Hazaribagh Plateau (Jharkhand), Appalachian

Plateau (USA).

(xi) Rejuvenated Plateau: Example Missouri Plateau (USA).

Plains: A relatively Hat and a low- lying land surface with least difference between its highest and lowest points is called a plain. These are-

1. Structural Plains are resulted due to the upliftment of a part of sea floor bordered by a continent, generally called as continental shelf. Plains of Russian platform, Great Plains of USA and central lowlands of Australia.
2. Erosional Plains are formed when an erect tract of physical feature such as mountains, hills, etc. are worn down by the process of erosion. Northern Canada, Northern Europe and West Siberia are examples of ice – eroded plains.       
3. Depositional plains are formed due to the massive deposition of sediments. It occured due to action of various agents, rivers, glaciers, winds, sea, waves, etc. The Indo-Ganga in the Indian subcontinent, the Huang. Ho Plains of North China, the Po River plains in Italy and Nile river plains.

Delta: The depositional feature of almost triangular shape at the mouth of a river debouching either in lake or a sea is called Delta.

1. Arcuate delta: Nile, Ganga, Rhine, Niger, Irrawady, Volga, Indus, Danube, Mekong, Po, Rhone, rivers make such delta.
2. Bird Foot Delta: Mississippi and Omo river makes such delta.
3. Eustarine delta: Narmada, Tapi, Amazon, Mackenzie, Vistuala, Elb, Seine, Hudson rivers make such delta.
4. Cuspate delta: Ebro river makes such delta.
5. Estuaries: The surrounding where fresh water from the land meets salt water from the ocean are called Estuaries. Narmada, Tapi rivers make estuaries.

Major Land Forms on the Basis of Geomorphic Agents