The study of the geologic structure of rocks is necessary to know the history and nature of rocks because the presence of minerals and the texture of soils depend on the structure of rocks. The oldest and the newest types of rocks are found in the geologic form of India.
The oldest rocks of the Archean age are found in peninsular India, while the other hand, the latest layered kilns of the Quaternary period are predominant in the plains. The formation of the latest rocks continues in the deltaic regions and coastal areas. The utility of the geological structure is in the form of metallic and non-metallic mineral exploitation and soil. There is a substantial variation in the geologic structure of India due to its formation in different chronological order.
In the diverse nation of India, six types of rocks are found in the geologic structure.
The names of all those rocks are:
- Archean rocks
- Dharwar rocks
- Cuddapah rocks
- Vindhyan rocks, (Upper Vindhyan rocks and Lower Vindhyan rocks)
- Gondwana Rocks
- Deccan Trap.
The Archean group of rocks is more than 500 million years old. It is the oldest group of rocks. In the ancient period, at the time of the earth's formation, the land was scorching, and when it gradually cooled down, the Rocks of the Archean order were formed.
The Archean rocks are also called igneous rocks. This is because these rocks are much older than human life. Due to the heat, pressure and land style, these rocks have been transformed. That is why the rocks of the Archean order are found in the form of granite, neiss, schist, phyllite, marble, quartz, dolomite etc.
The characteristic of the rocks of the Archean order is that they are fibrous, but there is a complete lack of fossils in them because the internal forces have had a lot of influence on these rocks.
Groups of these rocks are found over huge areas. It covers an area of about 1,87,500 sq.km. These rocks are found in the southeastern parts of Karnataka, Madhya Pradesh, Rajasthan, Odisha, Chhattisgarh, Jharkhand, Andhra Pradesh and Tamil Nadu.
Such rocks are also found in the deep part of the central Himalayas. It is noteworthy that two-thirds of peninsular India is formed from the Archean order.
In these, three complete civilizational rocks are found:
- Bengal Gneiss
- Bundelkhand Gneiss
- NilGiri Gneiss
Among these, Bundelkhand Gneiss is the oldest.
No significant tectonic movement occurred for a long time after the formation of the Vindhya rocks. When there was a worldwide Sardinian movement in the upper Carboniferous period, the collected material transferred through the rivers in the narrow valleys formed Gondwana rocks.
The expansion of Gondwana rocks in peninsular India and outer peninsular India is as follows:
In peninsular India, these rocks extend up to Rajmahal hills in the valley of Damodar river, Mahanadi range in Mahanadi valley, Godavari, Vanganga and Wardha river valleys.
Gondwana rocks are found in the Deccan part of Nagpur, Kutch,Kathiawar, western Rajasthan, Chennai, Cuttack, Vijayawada,Rajahmundry, Tiruchirappalli and Ramanathapuram. Thus this rock is mainly found in Bihar, Madhya Pradesh, Maharashtra and Andhra Pradesh.
The extent of rocks in the outer peninsular regions is not very clear. Such rocks are found in Kashmir, Sikkim, Darjeeling and Assam. Apart from India, these rocks are also discovered in its adjacent regions, such as Nepal, Pakistan, Bhutan, Afghanistan, etc. Outer peninsular rocks are pretty different from peninsular rocks.
The Gondwana rocks are handy from the point of view of economic importance. 98% of India's coal is found in these rocks. The sandstone obtained from the Gondwana rock is used to construct buildings. Apart from this, many minerals like clay soil, lignite coal, cement and chemical fertilizers etc., are obtained from these rocks.
Last Updated on: August 24, 2022
