Question

The oldest crust on the earth is found at \(\underline{\hspace{1cm}}\).

• A. mid oceanic ridge
• B. subduction zones
• C. sea floor spreading
• D. transform plate boundary

Hint:

Remember the conveyor belt analogy for oceanic crust: it's created at mid-ocean ridges (youngest), travels across the ocean floor, and is destroyed at subduction zones (oldest). The absolute oldest rocks on Earth are found on continents in areas called cratons.

Answer 1

The Correct Option is B

Step 1: Understand the life cycle of oceanic crust.
New oceanic crust is constantly being formed at mid-ocean ridges through the process of sea-floor spreading. This newly formed crust is therefore the youngest.

Step 2: Trace the movement and aging of the crust.
As new crust is formed, it pushes the older crust away from the ridge. Over millions of years, this older crust moves across the ocean floor until it eventually reaches a convergent plate boundary.

Step 3: Identify the location where the oldest oceanic crust is found.
At a convergent boundary, the dense oceanic crust is forced down, or subducted, beneath the less dense continental crust or another oceanic plate. This location is called a subduction zone. Therefore, the oldest oceanic crust is found at subduction zones, just before it is recycled back into the mantle.