N.K. Chauhan 
India's geographical land area can be classified into: Archaean System, Dharwar System, Cuddapah System, Vindhyan System, Gondwana System, Deccan Trap, Tertiary System and Quarternary System.
Archean rocks
Archean rocks, also known as Pre-Cambrian rocks are the oldest rocks of the earth's crust.The Archean period covers 86.7% of total geological history time of earth and therefore is very significant.
This period marks the development of first photosynthesis, the life support atmosphere.
The major characteristic of the Archean rocks is that they are azoid (devoid of any form of remnants of life).
The Archean rocks in India are found in Aravallis mountains, 2/3rd of the Deccan peninsula and some parts of north east.
These rocks have abundant metallic and non-metallic minerals such as iron, copper, manganese, bauxite, lead, zinc, gold, silver, tin, tungsten, mica, asbestos, graphite etc.
Dharwar system
Dharwar system rocks have been formed as a result of the erosion and sedimentation of the rocks of the Archaean system.These are the oldest sedimentary rocks.
The Aravali mountain range which is the oldest fold mountain of the world has been made with these rocks.
The rocks of this system are found in the districts of Dharwar and Shimoga in Karnataka.
The rocks of this system are also found in the southern Deccan region from Karnataka to the Kaveri valley, districts of Bellary, Shimoga, Sasar mountain range in Jabalpur and Nagpur and the Champaner mountain range in Gujarat.
The rocks of this system are economically very important (mosr mineralized). All prominent metallic minerals (iron, gold, manganese etc) are found in these rocks.
Iron ore in India is found mainly in Dharwar rocks system.
Cuddapah System
Cuddapah System rocks have been formed as a result of erosion and sedimentation of the rocks of Dharwar system, these are also sedimentary rocks.The rocks have been named after the district of Cuddapah in Andhra Pradesh where these are semi-circular in expansion.
These are famous for sandstone, limestone, quartzite, slateM marble and asbestos.
The Cuddapah rocks are also found in Rajasthan, Chhattisgarh, Delhi and the lesser Himalayas.
One of the important series of Cudappah System is Papaghani series, named after the river of same name in Andhra Pradesh.
Vindhyan System
Vindhyan System have been formed after the cuddapah rocks by the deposition of silt of river valleys and shallow oceans, these rocks are also sedimentary rocks.The evidences of fossils of micro-organisms are found in this structure.
This system rocks are extensively distributed in India from Chittorgarh (Rajasthan) to Sasaram (Bihar).
These rocks are found in the Vindhyas, e.g. the Malwa plateau, the Semari range in the Son valley, Bundelkhand etc.
This structure is famous for house-building rocks.
The Sanchi Stupa, the Red Fort, the Jama Masjid etc are built with the red sandstone of this structure.
Besides, limestone, china clay, dolomite etc are also found in this structure.
The diamond mines of Golconda in Karnataka and Panna in Madhya Pradesh are found in this structure.
The important series of this system are Bhander series, Bijwar series and Kaimur series, all are rich sources of Building material.
Gondwana System
Gondwana rocks have been formed between the Carboniferous and Jurassic periods.98% of coal in India is found in Gondwana structure.
The important coal bearing areas of this series are Raniganj, Jharia, Karanpur, and Bokaro of the Damodar basin in Odisha, and the Pench valley in Chhattisgarh and Madhya Pradesh, the jhingurda coal seam (Chhattisgarh).
Damodar and Sone river valley and Rajmahal hills in the eastern India is depository of the Gondwana rocks.
Deccan Trap
The volcanic action in the peninsular India began in the last period (Cretaceous period) of the Mesozoic era.Thus, the Deccan trap has been formed as a result of fissure eruption.
This structure is made up of basalt and dolorite rocks.
These rocks are very hard and their weathering has resulted in the formation of the black soil.
This structure is found in the most parts of Maharashtra and some parts of Gujarat, Madhya Pradesh, Andhra Pradesh and Tamil Nadu.
Tertiary System
Tertiary System rocks have been formed between the Eocene and Pliocene periods.The final break-up of the Gondwana land occurred in this era and the Tethys sea got lifted in the Himalayas.
Mineral oil in Assam, Rajasthan and Gujarat is found in the structures of the Eocene and Oligocene period.
The most important rocks of this system are in northern plains of India, karewas of Kashmir and bhadarwah, Bhangar, and Khadar of the Great Plains.
The rocks of this system are also found in coast of Kachchh, Katiawar, Konkan, Malabar, Nilgiri, and the Eastern Ghats.
