Module 2: Geological structure
Concept
Subtopic 2.1: Geological structure
- Bihar's rocks range from the Quaternary back to the Pre-Cambrian era.
- The alluvial plain is the newest structure. In the southern marginal plateau, Archean (very old) rocks are found.
- Four distinct surfaces: (1) Tertiary Siwalik rocks in the north; (2) Pleistocene alluvium of the Ganga plain; (3) Kaimur plateau with Vindhyan limestone and sandstone; (4) Archean rocks of the southern marginal plateau.
- The plain is about 95% of the state and developed over the ancient Tethys Sea.
- By the geosyncline theory, the Himalaya formed from the compression of Tethys sediments.
- A huge foredeep formed south of the Himalaya. Rivers coming from the plateau of Gondwanaland dumped sediments there, forming the Ganga plain in the Pleistocene.
- The plain is made of loose clay, silt and sand of varying grain size. Plate-like layers at depth give the underground water a special character.
⭐ Key Points
- The alluvial plain (Ganga plain) is the youngest structure.
- The southern border plateau (Chotanagpur side) carries Archean rocks.
- The plain, about 95% of the state, formed over the Tethys Sea.
- Kaimur is Vindhyan-age limestone and sandstone.
- Compression of Tethys Sea sediments raised the Himalaya.
- Sediments of rivers from the Gondwanaland plateau filled the foredeep in the Pleistocene.
📌 One-line Q&A
- Question: Which is the newest geological structure of Bihar? Answer: The alluvial plain.
- Question: Archean rocks are found in: Answer: Southern marginal plateau.
- Question: The Bihar plain developed over the ancient: Answer: Tethys Sea.
- Question: The Kaimur plateau consists of: Answer: Vindhyan limestone and sandstone.
- Question: According to the geosyncline theory the Himalaya formed by: Answer: Compression of Tethys sediments.
- Question: The Ganga plain was built in which epoch? Answer: Pleistocene.
Topic
MCQs
Answer this question, then use Next.
Question 1: Which is the newest geological structure of Bihar?
The alluvial plain (Ganga plain) is the youngest structure.
Question 2: Archean rocks are found in:
The southern border plateau (Chotanagpur side) carries Archean rocks.
Question 3: The Bihar plain developed over the ancient:
The plain, about 95% of the state, formed over the Tethys Sea.
Question 4: The Kaimur plateau consists of:
Kaimur is Vindhyan-age limestone and sandstone.
Question 5: According to the geosyncline theory the Himalaya formed by:
Compression of Tethys Sea sediments raised the Himalaya.
Question 6: The Ganga plain was built in which epoch?
Sediments of rivers from the Gondwanaland plateau filled the foredeep in the Pleistocene.
Question 1 of 6
One-liners
Write your answer, then submit to see the correct answer.
Which is the newest geological structure of Bihar?
The alluvial plain.Archean rocks are found in:
Southern marginal plateau.The Bihar plain developed over the ancient:
Tethys Sea.The Kaimur plateau consists of:
Vindhyan limestone and sandstone.According to the geosyncline theory the Himalaya formed by:
Compression of Tethys sediments.The Ganga plain was built in which epoch?
Pleistocene.
Question 1 of 6