Which type of rock is formed under conditions of high pressure?

Metamorphic rock is formed under conditions of high pressure and temperature, typically deep within the Earth's crust. This process is known as metamorphism, where existing rock types—either igneous, sedimentary, or even other metamorphic rocks—are transformed into new rocks. During metamorphism, minerals within the rock can change, and new minerals may form due to the increased heat and pressure. This process can lead to the characteristic foliation and banding found in many metamorphic rocks, such as schist and gneiss.

Igneous rocks, on the other hand, form from the cooling and solidification of molten rock (magma or lava), while sedimentary rocks form from the accumulation and compaction of sediment. Granite is a specific type of igneous rock that crystallizes from magma below the Earth's surface. Hence, while the other options describe significant rock types and formations, only metamorphic rocks are specifically associated with the high-pressure conditions essential for their formation.