PLATE TECTONICS — Oceanic vs continental crust age Statement: The oldest rocks found in ocean basins are ____ than the oldest continental rocks. Choose the best comparative term.

Introduction / Context:
The Earth's crust is not uniform. Oceanic crust is continually created at mid-ocean ridges and destroyed at subduction zones, whereas large parts of continental crust persist for billions of years. This question tests conceptual understanding of crustal recycling and the age distribution of rocks in different tectonic settings.

Given Data / Assumptions:

• Oceanic lithosphere forms at mid-ocean ridges and moves away as new crust forms.
• Old oceanic lithosphere is recycled into the mantle at trenches.
• Continental lithosphere is more buoyant and rarely subducts wholesale.
• We compare the oldest rocks in each setting, not the average age.

Concept / Approach:
If oceanic plates are continually created and destroyed, their maximum possible age is capped by the time it takes to reach a subduction zone and be recycled. Continental blocks, being buoyant and internally welded by multiple orogenies, can preserve ancient cratons for billions of years. Therefore, the oldest ocean-basin rocks must be significantly younger than the oldest continental rocks.

Step-by-Step Solution:
Recognize the plate-tectonic conveyor: creation at ridges, destruction at trenches.Infer that oceanic crust rarely survives beyond a couple of hundred million years because it will eventually subduct.Recall that continental shields (e.g., Archean cratons) retain rocks older than 3 billion years.Therefore, the correct comparative term is “younger.”

Verification / Alternative check:
Geochronology shows typical oldest oceanic crust is about 180–200 million years old, while continental crust commonly exceeds 2.5–3.5 billion years in shield areas. This drastic contrast confirms the reasoning.

Why Other Options Are Wrong:
Older — contradicts plate recycling evidence.Larger/Smaller — compare size, not age, and are irrelevant.More deformed — deformation varies and does not answer the age comparison.

Common Pitfalls:
Confusing “ocean-basin sediments” (which can include reworked older particles) with “oceanic crust” rock ages. The question is about the basement age, not the age of deposited sediments.

Final Answer:
younger