The Ninety East Ridge (90° East Ridge) is located in which of the following oceans?
- (a)Arctic Ocean
- (b)Atlantic Ocean
- (c)Pacific Ocean
- (d)Indian Ocean
Correct — D, Indian Ocean. The Ninety East Ridge is one of the longest and straightest submarine ridges on Earth, running roughly north-south along the 90°E meridian across the floor of the Indian Ocean, from the Bay of Bengal southward past Sri Lanka toward the Kerguelen Plateau area. It formed as the Indian Plate drifted northward over the Kerguelen hotspot.
- (a)Arctic Ocean — The Arctic Ocean's notable submarine feature is the Lomonosov Ridge, not the Ninety East Ridge.
- (b)Atlantic Ocean — The Atlantic's defining submarine feature is the Mid-Atlantic Ridge, a divergent plate boundary — a different ridge system.
- (c)Pacific Ocean — The Pacific's major submarine rise is the East Pacific Rise; the Ninety East Ridge is specific to the Indian Ocean floor.
The Ninety East Ridge is a hotspot-trail submarine ridge on the Indian Ocean floor, formed as the Indian Plate moved north over the stationary Kerguelen hotspot — the same hotspot volcanism linked to the Kerguelen Plateau. It runs for thousands of kilometres roughly along the 90°E meridian.
State PCS geography sections test ocean-floor relief features as direct recall — the trap is not knowing which of the four oceans hosts a particular named ridge, rise, or trench.
- Ninety East Ridge: Indian Ocean floor, aligned along ~90°E longitude
- One of the longest, straightest submarine ridges on Earth
- Formed by Indian Plate movement over the Kerguelen hotspot
- Runs from near the Bay of Bengal southward toward the Kerguelen Plateau region
The Ninety East Ridge is a defining submarine relief feature of the Indian Ocean floor.
- Confusing the Ninety East Ridge (Indian Ocean, north-south along 90°E) with the Mid-Atlantic Ridge or East Pacific Rise
- Assuming major submarine ridges exist only in the Atlantic
State PCS papers frequently test 'which ocean floor feature is located where' as direct recall of ocean-floor relief.
No directly related past PYQ was found.
- practice — not a real PYQ
The Chagos-Laccadive Ridge, a submarine ridge running roughly north-south, is located in which ocean?
- (a)Atlantic Ocean
- (b)Pacific Ocean
- (c)Indian Ocean
- (d)Arctic Ocean
Answer(c) Indian Ocean.
- practice — not a real PYQ
Mid-ocean ridges on the sea floor are primarily associated with which geological process?
- (a)Continental collision
- (b)Seafloor spreading at divergent plate boundaries
- (c)Subduction
- (d)Erosion by ocean currents
Answer(b) Seafloor spreading at divergent plate boundaries.