Quoc: Oceanic crust is continuously being created at mid-ocean ridges. As plates diverge at these ridges, magma rises into the upper mantle and crust. As it moves away from the ridge, the lithosphere becomes cooler and denser, and sediment gradually builds on top of it. The youngest oceanic lithosphere is at the oceanic ridges, and it gets progressively older away from the ridges.

Where would the oldest oceanic crust be found?
HW Chung: OK, some thoughts:
To answer this question, we should know that: The youngest oceanic lithosphere is at the oceanic ridges, and it gets progressively older away from the ridges. The answer is away from the ridges.