Question

Extrusive igneous rocks _____.

-form from confining pressure
-cool quickly on Earth's surface
-cool slowly beneath Earth's surface
-form layers called foliations

Answer 1

The correct answer is Cool quickly on Earth's surface.

Answer 2

Extrusive igneous rocks are formed by cooling lava. Since the temperature gradient between lava and Earth’s atmosphere is very big, cooling is very rapid. The second option is deemed true, which also means the third option is false. Foliations occur only in metamorphic rocks, deeming the forth option false. Since extrusive igneous rocks are formed at the surface of the Earth, there would be no confining pressure, which means the first option is false.