The combination of sial and sima constitute the

The combination of sial and sima constitute the lithosphere. Sial is the upper layer of the Earth's crust, which is composed of lighter rocks such as granite, while sima is the lower layer composed of heavier rocks such as basalt. The lithosphere is the solid, outermost layer of the Earth, which includes both the crust and the uppermost part of the mantle. It is the rigid layer upon which the Earth's tectonic plates move and interact with each other, causing earthquakes, volcanic eruptions, and the formation of mountains.