Geological Structure of India.pptx

Geological structure of INDIA

1. Mr. rahul Assistant professor of geography Smrj govt. pg college, siwani ( bhiwani )

2. Geological Structure of India The geological structure of a country helps in understanding the types and character of rocks and slopes, the physical and chemical properties of soils, the availability of minerals, and the surface and underground water resources. But before we can study the geological structure of India, it is important that we understand what a geological time scale

3. Geological Time Scale

4. Geological History of India: Major events in the geological history of India: Peninsular India was a part of the old landmass since the formation of the Earth’s Crust The upheaval of Himalayas in the tertiary period. Aggradational formation of the Indo- Gangetic plain during the Pleistocene period. It continues till today through sedimentation in the floodplains of the rivers and the lower part of the Gangetic plain.

5. The Archaean rock system (Early Pre-Cambrian) (a). Archaean Gneisses and Schists   These are the oldest rocks and were the first to be formed at the time of cooling and solidification of the upper crust of the earth’s surface in the pre- cambrian era. The rocks are primarily gneisses and granites, having no marks of fossils. T he system is generally known as the  basement complex or fundamental gneisses . This is the rock which mineral composition may vary from granite to gabro .

6. The central and the southern part of the Peninsula are occupied by this rock system. To the north-east of the peninsula, they occupy wide areas in Orissa, Meghalaya, Madhya Pradesh, Chhatishgarh , Chotanagpur plateau of Jharkhand and the whole of Bundelkhand. They also occur in roots of the mountain peaks all along the Himalayas , forming the bulk of the high ranges and the bacbone of the mountain system. Distribution of archaean rocks

7. (b). Dharwar Rocks These rocks are formed by erosion and depostion of primary Archaean rocks. First metamorphosed sedimentary rocks in Indian Geological Time scale. No fossils are found in these rocks. This system derives its name from the rocks first studied in the Dharwar district of Karnataka where such rocks are found in abundance . The Dharwar rocks are economically the most important rocks because they possess valuable minerals like high-grade iron ore, manganese, copper, lead, gold, quartzite, slates, mica, etc .

8. The Dharwar system is very well developed in the Dharwar -Bellary-Mysore belt of Karnataka. It also occurs in Jharkhand ( Ranchi,Hazaribagh ), Madhya Pradesh ( Balaghat,Rewa ), Chhatisgarh ( Baster,Dantewara,Kanker ), Orissa ( Sundergarh , Keonjhar ) and in the Aravalis between Jaipur and Palanpur . In the extra-Peninsular region, the Dharwar system is well represented in the Himalayas both in the central and northern zones as well as in the Meghalaya plateau. Distribution of dharwar rocks

9. 2.  The Purana Rock System (Late Pre- cambrian ) : In India, the word purana has been used in place of Proterozoic and includes two divisions: (a). Cuddapah system (b). Vindhyan system (a). The Cuddapah System: These rocks are formed after the erosional and depostional process of dharwar system. These rocks are also metamorphic sedimentary rocks. No fossils are found in these rocks. These formations, named after the Cuddapah district in Andhra Pradesh are sedimentary metamorphic formations. The economic significance of the Cuddapah system lies in the fact that these rocks contain ores of iron, manganese, copper, cobalt, nickel, jasper and asbestos. They also contain large deposits of building purpose quartzites and cement grade limestones . The metallic content in ores of Cuddapah rocks is low and at places uneconomical for extraction.

10. These are found in Andhra Pradesh, southern Chhattisgarh, Odisha and along the main axis of Aravallis . Distribution of cuddapah rocks

11. (b). The Vindhyan System: This system derives its name from the Vindhyan mountains. Rocks of this system are formed after the Cuddapah system. Consists of enormous sedimentary deposits. In some tracts, Vindhyan rocks are buried under the Deccan lava. Fossils are found in these rocks . The well-known diamond mines of Panna (Madhya Pradesh)and Golconda (Karnataka) lie in the Vindhayan system rocks. This rock system is well known for red sandstone, sandstone, durable stones, ornamental stones, raw materials for lime, glass, cement and chemical industries.

12. It stretches from Sasaram in Bihar to Chittorgarh in Rajasthan with the exception of the central tract of Bundelkhand gneiss . These rocks are also found in southern Chhattisgarh, Bhima valley of Karnataka and Kurnool districts of Andhra Pradesh. Distribution of vindhyan rocks

13. 3. The Dravidian Rock system (Cambrian to C arboniferous) The rocks of the Dravidian system came into being about 600-300 million years ago. These rocks are mostly found in the extra-Peninsular regions of the Himalayas and the G angetic plain except small patches. They contain abundant fossils in them Coal formation started in the Carboniferous age. Carboniferous in geology means coal-bearing. The rocks of Cambrian, Ordovician, Silurian, Devonian and Carboniferous periods are included in the Dravidian System.

14. 4. The Aryan Rock system The Aryan rock system comprises the rock formation ranging from the upper Carboniferous to recent. (a) Gondwana System (b). The Decan Trap (c) Tertiary System (d). Quarternary Formations

15. (a). The Gondwana System This system derives its name from the Gond region of Madhya Pradesh also where these rocks were first discovered. The peninsula during the Upper Carboniferous period experienced crustal movements, which led to the formation of basin-shaped depressions. These depressions had countless terrestrial plants and animals, which were buried to from coal deposits in India known as the Gondwana Rocks . Economically, the Gondwana rocks are the most important in India contaning about 98 percent of her coal reserves. They have rich deposits of iron ore, copper and uranium. Sandstones, slates and conglomerates are used as building materials.

16. These Rocks are found mainly along the Damodar valley in Jharkhand, along the Mahanadi river valley in Chhatisgarh and Orissa, in the southern part of Madhya Pradesh and the Godavari valleys of the peninsula. Distribution of Gondwana rocks

17. (b). The Deccan Trap: Towards the end of the Mesozoic era, intensive volcanic activity took place, which flooded with lava vast areas of Maharashtra and other parts of the Deccan known as the Deccan traps. The volcanic rocks contain some thin fossil ferrous sedimentary layers found between the lava flows. This indicates that the lava flows was not continuous. The volcanic activity led to two great events. 1.Breakup of the G ondwana landmass 2. Uplift of the Himalayas out of the Tethys Sea. The weathering of these rocks for a long time has given birth to black cotton soil known as ‘ regur ’.

18. Deccan Trap covers about 5 lakh sq km mainly in parts of Kuchchh , Saurashtra , Maharashtra, the Malwa plateau and northern Karnataka. Distribution of decan trap

19. (c). Tertiary System Eocene to Pliocene about 60 to 7 million years ago. The tertiary is the most significant period in India’s geological history because the Himalayas were born and India’s present form came into being in this period. The Tertiary has been called the age of the Mammals because of the abundance of the fossils remains of these animals in the deposits of this period.

20. (d). The Pleistocene and recent formations (The quaternary period) Quaternary is the name proposed for very recent deposits, which contains fossils of species with living representatives These include Satluj -Ganga-Brahmaputra plains and Karewa formations of the Kashmir valley.

21. Thanks