Earth layers (Sial vs. Sima): The heavier silicates called “Sima” (silica + magnesium) are most abundant in which part of Earth? Think of basaltic composition and oceanic crust distribution. Choose the correct option.

Given data

• Identify where silica–magnesium (sima) materials dominate.

Concept/Approach
In classical physiography, sial (Si + Al) characterizes continental upper crust (granitic), whereas sima (Si + Mg), akin to basaltic composition, dominates the oceanic crust forming the ocean floors. The mantle is ultramafic (peridotitic) and not what is meant by sima in this context.

Final Answer
Ocean floors