Question

Which of the following is an example of an old folded mountain?
A. Aravalli
B. Himalayas
C. Eastern Ghats
D. Western Ghats

Answer 1

Hint: A natural elevation of the earth surface is broadly referred to as a mountain. Categorically, however, a landform that rises at least 1,000 feet (300 meters) or more above its surrounding area is defined as a mountain. Based on their origin, there are three kinds of mountains— fold mountains, block mountains and volcanic mountains. Fold mountains are formed due to the convergence of tectonic plates in the earth’s crust. At the boundaries where the plates collide, rocks and debris are accumulated and folded into rocky hills, mountains, and ranges.

Complete answer:
Option A: is correct. The Aravallis are the oldest folded mountain range in the Indian subcontinent. The range begins at Delhi and stretches over from Southern Haryana and Rajasthan to Gujarat running almost 700 km in length. It contains Proterozoic rocks that were formed when the Indian Plate separated from the Eurasian Plate.
Option B: is incorrect. The Himalayas are the largest mountain range in the world that are geologically young and structurally folded. The range runs from the river Indus in the north-west to the river Brahmaputra in the east and is present in five Asian countries namely Pakistan, China, India, Nepal and Bhutan.
Option C: is incorrect. The Western Ghats or Sahyadri that stretches over 1600 km parallel to the western coast of India is a structurally block mountain range formed due to faulting and erosion.
Option D: is incorrect. The Eastern Ghats is a discontinuous range parallel to the eastern coast of India and is made up of thrusts and faults.
Hence, the correct answer is, ‘A. Aravalli’.

Note: An orogenic movement leads to the upliftment of continental plates and the formation of mountain ranges. It takes place due to the convergence of tectonic plates in the earth’s crust. On the other hand, epeirogeny is the vertical movement of a continent by faulting or isostasy. The broad central parts of continents called cartoons are formed due to epeirogenic movements.