RAS question
The 'Great Boundary Fault' in Rajasthan separates:
Correct answer: (C) Vindhyan from Aravalli.
In Rajasthan, the Great Boundary Fault separates the Vindhyan system from the Aravalli system.
Explanation
The Great Boundary Fault is a geological boundary in eastern Rajasthan that marks the contact between two major rock systems: the Vindhyans and the Aravallis. The official groundwater resource report states that the Vindhyan Super Group occurs in separate basins on either side of the Aravallis and that the Great Boundary Fault separates the Vindhyans from the Aravallis and older Archaean rocks. This matches the standard RAS framing: the fault is not a political, regional, or desert-hill divide, but a structural line between geological provinces. The same report places the Vindhyan scarplands along the Great Boundary Fault from Chittorgarh eastwards, which supports the explanation that the feature is important in eastern Rajasthan's physiography.
Why the other options are wrong
- (A) The Thar-Aravalli contrast is a desert-versus-hill physiographic contrast, while the cited report identifies the Great Boundary Fault as separating the Vindhyans from the Aravallis, not the Thar from the Aravalli range.
- (B) Marwar and Mewar are regional-historical labels, whereas the Great Boundary Fault is described in the source as a geological boundary involving the Vindhyan and Aravalli rock systems.
- (D) Hadoti and Mewar are regional divisions, but the explanation and the cited report both tie the fault to the Vindhyan-Aravalli geological contact rather than a Hadoti-Mewar boundary.
Concept
This tests Rajasthan's physiography and geological structure, especially the way major faults and rock systems shape eastern Rajasthan. It recurs in RAS because such boundaries link physical geography with drainage, relief, and regional geology.