The Geological makeup of a nation provides insights into the nature of rocks and inclines, the physical and chemical attributes of soils, the presence of valuable minerals, as well as the availability of surface and subterranean water resources.
Physical Formation of India:
- This ongoing northward movement of the Indian plate has had significant implications for the physical landscape of the Indian subcontinent.
- Now, let us delve into the Geological structure of India, which can be broadly classified into three main regions:
(i) The Peninsular Block.
(ii) The Himalayas.
(iii) The Indo-Ganga-Brahmaputra Plain.
The Peninsular Block:
- The plateau of Peninsular India showcases a complex array of geological structures, encompassing some of the world’s oldest rocks dating back to the Precambrian period, as well as the youngest rocks from the Quaternary period.
- Since the Cambrian period, the Peninsula has maintained a relatively stable block-like structure, with exceptions along its western coast submerged beneath the sea and some areas experiencing tectonic activity that has not affected the original underlying foundation.
- Vertical movements and block faulting have played a significant role in shaping the landscape. Examples of these geological features include the rift valleys of the Narmada River, relict and residual mountains like the Aravali hills, and block faults such as the Malda fault in Eastern India.
- This region encompasses a diverse range of rock types, including igneous, metamorphic, and sedimentary rocks. For example, sedimentary rocks like limestone and sandstone can be found in river valleys.
- The coal deposits in the Peninsular India were formed during the Gondwana period. The black soil found in the Deccan region is a result of extensive lava flows during the Cretaceous period.
- The northern boundary of the Peninsular Block follows an irregular line, starting from Kutch and running along the western flank of the Aravali Range near Delhi.
- It then roughly parallels the Yamuna and Ganga rivers until it reaches the Rajmahal Hills and the Ganga delta . Additionally, extensions of this block can be found in Rajasthan to the west and the Karbi Anglong and Meghalaya Plateau in the northeast.
- The northeastern parts of the block are separated by the Malda fault in West Bengal from the Chotanagpur plateau. Rajasthan is characterized by desert and desert-like features that overlay this block.
- The Himalayas are a relatively young and geologically flexible mountain range, characterized by fold structures, in contrast to the rigid and stable Peninsular Block.
- The breakup of the supercontinent Pangaea, approximately 200 million years ago, resulted in the formation of the long Tethys Sea situated between the Laurentian Shield and Gondwanaland. This sea occupied the region of the Himalayas known as a geosyncline.
- Around 65-30 million years ago, the Indian plate approached the Eurasian plate and began subducting beneath it .
- This process of subduction caused lateral compression, leading to the squeezing and folding of the Tethys sediments into three parallel ranges that now form the Himalayas.
- Due to the ongoing northward movement of the Indian plate, these mountains are still subject to internal geological forces, in addition to external forces.
- It is believed that the height of the Himalayan peaks continues to increase as a result of these processes.
- The Himalayas consist of four litho tectonic mountain ranges, namely
(i) the Trans-Himalaya.
(ii) the Greater Himalaya.
(iii) the Lesser Himalaya.
(iv) the Shiwalik.
- The first phase of uplift produced the ranges of Trans Himalayas around 65 million years ago. Subsequent uplift led to formation of Greater Himalayas, Lesser Himalayas and Shivalik mountain ranges.
Syntaxial Bends of the Himalayas:
- At both ends of the Himalayas, distinct changes in structures and trends can be observed, forming bends known as “syntaxes.”
- These bends occur in areas where two colliding tectonic plates meet, in the vicinity of active collision zones.
- The western syntaxial bend is located near Nanga Parbat, where the Indus River has carved a deep gorge.
- In this region, geological formations exhibit sharp hairpin bends, as if they were contorted around pivotal points.
- Similarly, a hairpin bend can be observed in Arunachal Pradesh, where the mountains abruptly change direction from east to south after crossing the Brahmaputra River.
- The third geological division of India comprises the plains located south of the Shiwalik range, which were formed by the Indus, Ganga, and Brahmaputra river systems.
- Originally, it was a depression known as a geosyncline, which reached its maximum development during the third phase of Himalayan mountain formation around 64 million years ago.
- This region is characterized by an aggradational plain formed by the accumulation of alluvial deposits from rivers originating in the Himalayas to the north and the Peninsular plateau to the south.
- Over time, these plains have been gradually filled with sediments carried by the rivers from both regions. The average depth of alluvial deposits in these plains ranges from 1,000 to 2,000 meters.
- Some geologists suggest that the Great Plains are remnants of the ancient Tethys Sea.
- After the uplift of the Shiwalik range, the remaining portion of the Tethys Sea formed a large trough.
- As the Himalayas continued to rise, the rivers experienced increased erosion and transported larger amounts of sediment, leading to the thickening of the alluvial deposits in the plains.
Physiography Division of India
- ‘Physiography’ refers to the examination of the Earth’s surface features and landforms. It is influenced by the structural composition, ongoing processes, and the stage of development.
- In India, there are significant variations in the geological structure across different regions.
- The relief and physiography of India have been shaped by geological and geomorphological processes occurring in the subcontinent.
- The physical characteristics of India exhibit great diversity. The northern region showcases an expansive and rugged topography, characterized by a series of mountain ranges with diverse peaks, picturesque valleys, and deep gorges.
- In contrast, the southern region consists of stable tablelands with dissected plateaus, exposed rocks, and well-formed escarpments.
- Between these two regions lies the vast expanse of the North Indian plain. Considering these broad variations, India can be divided into six distinct physiographic divisions.
- What is the geological structure of India?
- Answer: The geological structure of India refers to the composition, arrangement, and formation of rock layers and geological features within the country.
- Why is the study of India’s geological structure important for UPSC aspirants?
- Answer: Understanding India’s geological structure is crucial for geography and environmental science topics in UPSC exams, as it helps in comprehending natural resource distribution, landforms, and seismic activities.
- What are the key geological features of India that UPSC candidates should be aware of?
- Answer: Important features include the Himalayan mountain range, the Deccan Plateau, the Western and Eastern Ghats, the Indo-Gangetic Plain, and various geological fault lines.
- How has India’s geological history shaped its current landforms and topography?
- Answer: India’s geological history involves tectonic movements, continental drift, and sedimentation, which have contributed to the formation of its diverse landforms.
- What are the major mineral resources associated with India’s geological structure?
- Answer: India is rich in minerals like coal, iron ore, bauxite, and limestone, which are often linked to its geological features.
भारत की भूवैज्ञानिक संरचना (Geological Structure of India in Hindi) FAQs:
- भारत की भूवैज्ञानिक संरचना क्या है?
- उत्तर: भारत की भूवैज्ञानिक संरचना से भारत के भीतर पत्थर परतों और भूवैज्ञानिक विशेषताओं का संरचन, व्यवस्थित रूप, और गठन सम्बंधित है।
- UPSC प्रारंभिक परीक्षाओं के लिए भारत की भूवैज्ञानिक संरचना का अध्ययन क्यों महत्वपूर्ण है?
- उत्तर: भारत की भूवैज्ञानिक संरचना की समझ UPSC परीक्षाओं में भूगोल और पर्यावरण विज्ञान के विषयों में महत्वपूर्ण है, क्योंकि यह प्राकृतिक संसाधन वितरण, भूभूतियों, और भूकंप गतिविधियों को समझने में मदद करता है।
- भारत की भूवैज्ञानिक संरचना के मुख्य भूवैज्ञानिक विशेषताएँ क्या हैं जिनका ज्ञान UPSC उम्मीदवारों को होना चाहिए?
- उत्तर: महत्वपूर्ण विशेषताएँ हिमालय पर्वत श्रृंग, दक्कन पठार, पश्चिमी और पूर्वी घाट, इंडो-गढ़विक समतल, और विभिन्न भूवैज्ञानिक दोष रेखाएँ शामिल हैं।
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- उत्तर: भारत का भूवैज्ञानिक इतिहास पृथ्वीकी गतिमान, महाद्वीप के अद्भुत भूभागों के निर्माण में योजना, जल-वेग, और रेज़िमेंटेशन का सामिल होना सहित दिनिया भूस्थितियों के निर्माण में योगदान किया है।
- भारत की भूवैज्ञानिक संरचना के साथ संबंधित मुख्य खनिज संसाधन क्या हैं?
- उत्तर: भारत में कोयला, लोहा अयस्क, बॉक्साइट, और चूना पत
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