Correct Option
The correct option is 1 and 3 only.
Explanation
The lithosphere is the rigid, outermost mechanical layer of the Earth. It is distinct from the chemically defined "crust." The lithosphere behaves as a brittle solid and rests upon the weaker, semi-plastic asthenosphere.
Statement-wise Analysis
- Statement 1 is Correct: The thickness of the lithosphere varies depending on whether it is oceanic or continental. The oceanic lithosphere is thinner, typically ranging from approximately 5 km (near mid-ocean ridges where new crust is generated) to about 100 km in older, cooler ocean basins.
- Statement 2 is Incorrect: The continental lithosphere is much thicker than the oceanic lithosphere. It is not 10 km; rather, the continental crust alone has an average thickness of around 30 km (reaching up to 70 km in mountainous regions like the Himalayas). The total thickness of the continental lithosphere generally ranges up to 200 km.
- Statement 3 is Correct: The lithosphere is defined by its mechanical properties. It includes the entire crust (oceanic or continental) and the uppermost solid part of the mantle (above the asthenosphere).
Key Takeaway
Key Takeaway: The lithosphere is the rigid outer layer comprising the crust and the top solid mantle. It is significantly thinner under the oceans (5-100 km) compared to the continents (up to 200 km).