Geological Structure of Bihar

Monday, August 3, 2020

Bihar is situated between 24° 20' 10" North & 27° 31' 15" North latitudes and 83° 19' 50'' East & 88° 17' 40'' East longitudes. It is 483 Km long (East to West) and 345 Km wide (North to South). Bihar is 12th largest state in India having total area of 94,163 Sq. Km. 
Bihar is situated between the humid, West Bengal (in East) and the sub-humid, Uttar Pradesh (in West) . Hence Bihar has transitional climate between humid and and sub-humid.
Bihar has total population of about 10,40,99,452 (according to Census 2011). This humongous population makes Bihar 3rd largest state of India and constitute about 8.6% of total population of India. Out of those 88.7% of population of Bihar live in Rural areas and rest of 11.3% live in Urban regions.

Geological Structure of Bihar

Bihar has balanced picture of geological formations which consists of oldest formation i.e. Dharwar Rock System in Southern part of Bihar bordering Jharkhand as well as youngest rock formations i.e. Quaternary Rock System found in Central Part of Bihar (in between Dharwar System and Tertiary rock system of North-Western Terai Region of Bihar).
The (geological structure of Bihar can be divided into 4 parts:-  
  1. Dharwar Rock System
  2. Vindhyan Rock System
  3. Tertiary Rock System
  4. Quaternary Rock System

Dharwar Rock System

Dharwar Rock formation is a subsystem of  the oldest Archaean Rock System, which was formed between 3100-2100 million years ago (3.1-2.1 Arab years ago). 
The Southern parts of the districts of Aurangabad, Gaya, Nawada, Jamui and Munger in Bihar are formed out of this Dharwar Rock System.
It is named after Dharwar district of Karnataka, where it is found in abundance.
This rock system formed of Quartzite, Phyllite, Gneiss, Schist, Shale and Slate. The region has abundance of Schist and Mica.

Vindhyan Rock System

This is a subsystem of the Purana Rock System which is developed during 1300-600 million years ago (1.3-0.6 Arab years ago). This rock system is named after Vindhyan Ranges. Vindhyan rocks are formed out of Sandstone, Limestone, Dolomite, Quartzite and Shale.
It has large deposits of Pyrite and Limestone which are used for commercial purposes.
  • Vindhyan Rocks are found in Kaimur District and the Son Valley of Rohtas district.

Tertiary Rock System

This rock system is formed during the period of development Himalayan Ranges. These are formed between 60-7 Million years ago (6-0.6 crore years ago).
Tertiary Rock System in Bihar is found in the Upper North-Western parts of Bihar or the Terai Region of Shivalik Ranges in Bihar in Western Champaran districts.
These are formed due to down warping of Sediments in the Tethys Sea between Eurasian Plate and Indian Plate.
This Rock System is formed out of Sandstone, Sandy Shale, Mudstone and Conglomerate.
Also Read: Climate of Bihar

Quaternary Rock System

This rock system is formed during the recent Pleistocene period in last one Million (10 lakh years) and its formation is still in continuation.
This rock system is formed due to deposition of alluvium brought swiftly by Himalayan and Peninsular rivers such as, Ghaghra, Gandak, Koshi, Bagmati, Koshi, Son, Mahananda, Punpun and of coarse the Ganga River, which slowly deposited and compressed resulting into formation fo the Quaternary rocks.
Quaternary Rocks are formed out of sandstone, conglomerate, coarse gravels etc.
It is found between Himalayan Terai Region of Bihar in the North and Chhotanagpur plateau region in the south.