Formation
* India has been formed over several geological periods.
* According to the theory of Plate Tectonics, the earth’s crust was formed out of seven major and some minor plates.
Tectonic plates are classified into:
* Convergent boundary
* Divergent boundary
* Transform boundary
* Gondwanaland originally consisted of Asia, Africa, South America and Australia all joined together.
* The Himalayas were formed by the collision of the Indian plate with the Eurasian plate. This collision also created the Northern Plains.
* The oldest physical feature of India is the Peninsular Plateau.
The Himalayas
* The Himalayas are geological young, Fold Mountains.
The Himalayan Mountains contains of three parallel ranges:
* The Great or InnerHimalayas or the Himadri
* The Lesser Himalayas or the Himachal
* The Shiwaliks
Going west to east, the Himalayas can be divided into a number of regions demarcated by rivers:
* The Punjab Himalayas are located between the Indus and Sutlej rivers.
* The Kumaon Himalayas are located between the Sutlej and the Kali River.
* The Nepal Himalayas are located between the kali and the Tista Rivers.
* The Assam Himalayas are located between the Dihang Rivers.
* The Purvanchal area is bounded by the Brahmaputra. This region is made up of the Patkai hills, the Naga Hills, the Manipur hills and the Mizo hills.
The Northern Plain
* The Northern Plain consists of the region at the south of the Himalayan mountain range.
The plain is formed from the flood plains of three big river systems:
* The Indus
* The Ganga
* The Brahmaputra
* The Northern Plain is one of the worlds’ most intensively farmed areas.
The Northern Plain can be divided into three main parts:
* The Punjab Plains, formed by the Indus and its tributaries
* The Ganga Plain between the Ghaggar and the Teesta
* The Brahmaputra Plain lying in the state of Assam
* The states that fall under the Northern Plain are: Punjab, Haryana, Delhi, Uttar Pradesh and Bihar, parts of Jharkhand and West Bengal and Assam.
The Northern Plains can be divided into four regions:
* Bhabar
* Terai
* Bhangar
* Khaddar
The Peninsular Plateau
* The Peninsular Plateau is a tableland. It was formed when Gondwanaland broke and the pieces drifted apart.
The Peninsular Plateau has two broad divisions:
* The Central Highlands
* The Deccan Plateau
* The Central Highlands refer to the portion of the Peninsular Plateau lying to the north of the Narmada River. It covers a majority of the Malwa Plateau.
* The Deccan Plateau is a triangular landmass lying to the south of the Narmada.
* In the south, the Deccan Plateau is bordered by the Western Ghats and the Eastern Ghats.
* The Western Ghats are tall, and lie parallel to the western coast. They are continuous and can be crossed through passed only.
* The Eastern Ghats are discontinuous and irregular, interspersed with several rivers.
* Orographic rainfall is caused when a range of mountains intercepts rain-bearing monsoon winds.
* The Western Ghats cause orographic rainfall on their western side.
* The black soil area of the Peninsular Plateau is known as the Deccan Trap.
* On the western and north-western margins of the plateau are the Aravali Hills. The Indian Desert, the Coastal Plains and the Islands
* The Great Indian Desert is an undulating sandy plain covered by barchans and longitudinal sand dunes.
The western coastal area runs along the Arabian Sea and is divided into three sections:
* Konkan
* The Kannad Plain
* The Malabar Coast
The eastern coastal region runs along the Bay of Bengal and is categorized into:
* The Northern Circars
* The Coromandel Coast
* The Mahanadi, the Godavari, the Krishna and the Kaveri rivers have formed a wide delta on the eastern coast.
* Lake Chilika on the eastern coast is the largest salt water lake in India.
Off the mainland, the country consists of two groups of islands:
* The Lakshadweep Islands
* The Andaman and Nicobar Islands
* The Lakshadweep Islands consists of small coral islands.
Three main kinds of reefs are:
* Barriers reef
* Fringing reef
* Atolls
* The Andaman and Nicobar Islands are a long chain of Islands extending from north to south, located in the Bay of Bengal.
* India’s only active volcano is found on the Andaman and Nicobar Islands.
Introduction to Drainage System
* A drainage basin is an area drained by a single river system.
* The drainage basin works as a funnel, by collecting all the water within the area and channeling it into a waterway.
* Himalayan rivers are perennial, whereas Peninsular rivers are seasonal.
* This upland area is known as a water divide.
* Drainage systems in India can broadly be categorized as Himalayan rivers and Peninsular rivers.
The four main patterns are:
* Dendritic Drainage
* Rectangular Drainage
* Trellis Drainage
* Radial Drainage
Himalayan Rivers
* The three important Himalayan Rivers are the Ganga, the Brahmaputra and the Indus.
* The main tributaries of the Indus are the Sutlej, the Beas, the Ravi, the Chenab and the Jhelum.
* The Ganga starts off as the Bhagirathi and is joined by the Alaknanda at Devaprayag.
* The major tributaries of the Ganga are the Yamuna, the Ghaghara, the Gandak and the Kosi.
* The Brahmaputra is slightly longer than the Indus, and flows its course eastwards, parallel to the Himalayas and mostly outside of India.
* The Brahmaputra gathers strength through its tributaries, the Dihang , the Dibang and the Lohit.
Peninsular Rivers
* The Western Ghats make up an important water divide in peninsular India.
* The major rivers are the Mahanadi, the Godavari, the Krishna and the Kaveri, which flow eastwards and drain into the Bay of Bengal.
* The two major rivers that flow westward and drain in the Arabian Sea are the Narmada and the Tapi.
* The Godavari is the longest and the largest peninsular river.
* The Krishna River is the second longest peninsular river.
Importance of Lakes and Rivers
* Lakes are important of several reasons, like regulating the flow of river water storage of water during the dry seasons, maintaining the ecosystem and also for the generation of hydroelectric power.
* The Wular Lake in Jammu and Kashmir is the largest freshwater lake in India.
* Other fresh water lakes include the Dal in Jammu and Kashmir, and the Bhimatal and Nainital lakes in Uttarakhand.
* The Sambhar Lake in Orissa is the largest back water lagoon in India.
* Rivers are considered the most basic natural resources required for human settlement.
* The government has launched activities such as the NRCP and GAP to save our lakes and rivers.