Under what conditions do metamorphic rocks typically form?

Metamorphic rocks typically form under conditions of high temperature and pressure. This process, known as metamorphism, occurs deep within the Earth's crust where both temperature and pressure are significantly elevated compared to surface conditions. The original rock, known as the protolith, undergoes physical and chemical changes due to these intense conditions, resulting in a new rock type with distinct mineralogical and textural characteristics.

High temperatures can cause minerals to recrystallize, while increased pressure can lead to the alignment of minerals, creating foliation or banding in the rock. This transformation does not involve melting; instead, the rocks remain solid and change in structure and composition due to the environmental conditions.

In contrast, the other options pertain to processes that do not typically produce metamorphic rocks. Low temperature might not provide enough energy for significant metamorphic changes, while cooling of magma relates to the formation of igneous rocks, and accumulation of sediments leads to the formation of sedimentary rocks.