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Geologic time scale Supereon>Eon>Era Period>Epoch>Age Beginning of Pre-Chambrian Supereon It lasted for nearly 4 billion years Ordovician Period (500 m) * Silurian Period (440 m) Cretaceous (136 m) Cenozoic Era (70-0 m) Hadean Eon Archean Eon Proterozoic Eon Devonian Period (395 m) Carboniferous (345 m) Permian Period (280 m) Mesozoic Era (225-70 m) Triassic Period (225 m) * Jurassic Period (195 m) Paleogene Period * Neogene Period * Quaternary Period Pleistocene epoch (I m) Phanerozoic Eon Paleozoic Era (570-225 m) . V Stone Age Cambrian Period (570 m) Holocene (10,000 y)
Earth's Interior Litosphere (solid) Mantle (solid) 2900km Important theories Astenosphere (plastic, molten) Continental crust (-50km) Liquid core (50km) Polar wandering (Similar to Continental Drift Theory) Continental Drift Theory (CDT) Convectional Current Theory (CCT) Sea Floor Spreading Theory (SFST) Plate Tectonics (PI) Solid core (6378km) Ocean crust(
Laurasia and Gondwana Modern world Pangaea North America Eurasia Eurasia Eurasie rica ocean Africa Africa Tethys ocean rica Teth ocean Am Indian ocean lia ia tarctic Antar
LAURASIA ETHYS SEA PERMIAN 225 million years ago TRIASSIC 200 million years ago URASSIC 150 million years ago CRETACEOUS 65 million years ago PRESENT DAY
ajor 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. Based on this complex and varied geological history, the Geological Survey of India has classified rock systems of the country into 4 major divisions: responding period on th s Geo Classification timescale 1. Archaean 2. Purana 3. Dravidian Early Precambrian Eon Late Precamb 600-40omya (largely coinciding with the Palaeozoic era) 400mya present or Proterozoic Eon 4 Aryan
I N D I A Geological Map CHN A TIBET Alluvial Upland(Old) BHUTAN Vindhan old) Trop Granites Crystalline BAY Deccan Trap BENG AL ARABIAN SEA ege Granites [ Recent and Pleistcene Tertiary Deccan Trap Staline Map not to Scale SRE INDIAN LANKA O C E A N 2007
Geological Divisions of India: Geologic divisions are marked by geologists as regions of similar rocks, structures and geologic history Geologically, India is divided into 3 major regions (also called the Triple Tectonic division): The Peninsular Plateau region - It also includes the Shillong Plateau and the Kutchch Kathiawar region (Outliers) The Extra-peninsular region - the mountainous region of Himalayas.
- The Himalayas are young, weak and flexible in their geological structure, unlike the rigid and stable Peninsular Block. - Consequently, they are still subjected to the interplay of exogenic and endogenic forces, resulting in the development of faults, folds and thrust plains. These mountains are tectonic in origin, dissected by fast-flowing rivers which are in their youthful stage. Various landforms like gorges, V-shaped valleys, rapids, waterfalls, etc. are indicative of this stage. . The Indo-Gangetic Plain between the above two. In addition to these,there are 3 minor divisions - The Coastal Plains (Eastern and western) . The Islands (Lakshadweep and Andaman and Nicobar)
Archaean Era (Pre Cambrian Period) Geologically, the subcontinent of India was a part of the Gondwanaland (the Southern Continent). The geological history of India is described in the below sections:
87% of the Earth's history is of this period (4.6 billion years ago till 570 million years ago). Archean means "oldest rocks of the Earth's crust". This period saw the development of the Earth's atmosphere, the first photosynthesis, first chemosynthesis and formation of the life supporting atmosphere. Throughout the world the rocks of this period are called as "Fundamental Geinesses" OR "Basement complex". They are devoid of any form of life or sediment and form the core of all great fold mountain ranges of the worl Archaean rocks are the repo sitories of the mineral wealth of India. These rocks are rich in ferrous and non-ferrous minerals Like iron ore, copper, manganese, mica, dolomite, lead, zinc, silver and gold. The Archaean rocks cover two-thirds of Peninsular India.
DHARWAR SYSTEMM This geologic time extends from 2500 million years ago to 1800 million years ago. These are the first metamorphosed sedimentary rock systems in Indian geological time scale. The Dharwar rocks are highly metalliferous. They are rich in iron ore, manganese, lead, zinc, goLd, silver, dolomite, mica, copper, tungsten, nickel, precious stones and building materials. Some of the important series of the Dharwar System are: - Champion Series - Its gold mines are one of the deepest in the world, Champaner Series - It is an outlier of the Aravalli system in the vicinity of Vadodra. An attractive green variety of marble is obtained from this series Chlipi Series - It occupies parts of Balaghat, jabalpur and Chhindwara districts of Madhya Pradesh. Closepet Series, Iron-Ore Series, Khondolite Series, Rialo Series, Sakoli Series, Sausar Series.
THE PALAEOZOIC GROUP (CAMBRIAN TO CARBONIFEROUS PERIOD) - This is known as the Dravidian Era in the Indian Geological Time Scale The Palaeozoic Era extends from 570 million years ago to 24.5 million years ago. It marks the beginning of life on the Earth's surface. . It was during this period that the Pangaea was broken and the Tethys Sea came into existence.
THE CRETACEOUS SYSTEM (THE DECCAN TRAP) This period is marked by the transgression of the sea (Coromandal coast, Narmada valley) and outpouring of huge quantity of lava (basalt) so as to form the Deccan Trap. During this period, enormous quantity of basaltic lava was poured out to the surface assuming a great thickness of over three thousand metres. The Lava Plateau (the Deccan Trap) is the result of that lava eruption. . The lava plateau of India (Deccan Trap) has a maximum thickness of about 3000 m along the coast of Mumbai from where it decreases towards south and east
THE TERTIARY SYSTEM (THE CENOZOIC ERA) Cenozoic means recent life. The beginning of the Tertiary Period js about 65 million years ago. Fossils in these rocks include many types, closely related to modern forms, including mammals, plants and invertebrates. .During this Period, as India collided with Tibet, the sediments which had been accumulating in the Tethys basin had begun to rise by a slow rise of ocean bottom. The upheaval of the Himalayas altered the old topography of the subcontinent. There is enough evidence to prove that the Himalayas are still rising.
Formation of Himalayas. Tibet Plateau India Sub-Continent Eurasian Continent Lithisphere Lithosp here Asthenosphere Ancient Oceanic Crust Continents Convergence