The correct option is 1, 2 and 3 only
Explanation
The Peninsular Block is formed essentially by a great complex of very ancient gneisses and granites. As a part of the Indo-Australian Plate, it has been subjected to various vertical movements and block faulting. The plateau consists of broad and shallow valleys and rounded hills. Many of the hills found here are classified as relict or residual mountains, which are the remnants of ancient mountain ranges that have been lowered by denudation (erosion) over geological time.
Statement-wise Analysis:
- 1. Aravali hills: Correct. The Aravali hills are one of the oldest fold mountain ranges in the world. Over millions of years, they have been extensively eroded and are now present as relict or residual mountains marking the northwestern boundary of the Peninsular Block.
- 2. Nallamala hills: Correct. The Nallamala hills are a section of the Eastern Ghats located in Andhra Pradesh. The Eastern Ghats are a discontinuous range of mountains that have been eroded by east-flowing rivers. They are considered relict mountains of the Peninsular plateau.
- 3. Javadi hills: Correct. The Javadi hills are located in Tamil Nadu and are also part of the Eastern Ghats. Like the Nallamala hills, they are residual features resulting from the erosion of the ancient plateau edge.
- 4. Satpura range: Incorrect. While the Satpura range is an ancient feature of the Peninsular Block, structurally it is classified as a Block Mountain (Horst) formed by rifting, situated between the rift valleys of the Narmada and Tapi rivers. In the context of physiographic classification within standard, the Aravali, Nallamala, and Javadi hills are explicitly grouped as examples of relict mountains, whereas the Satpura is distinguished by its block structure.
Key Takeaway:
The Aravali hills and the various ranges of the Eastern Ghats (Nallamala, Javadi, Veliconda, Palkonda) are classic examples of relict (residual) mountains formed by the erosion of ancient highlands. The Satpura and Vindhya ranges are primarily Block Mountains (Horsts) associated with rift valleys.