Assertion: continent's crust | /r/MadeOf | lighter sialrocks
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Source sentences:
text: According to the theory of plate tectonics, which has been extensively confirmed since the 1970s, the Earth's crust consists of lighter "sial" rocks (continental crust rich in aluminium silicates) that float on heavier "sima" rocks (oceanic crust richer in magnesium silicates).