Final answer:
Metamorphism is driven by changes in pressure and temperature, which lead to recrystallization of minerals and changes in rock texture.
Step-by-step explanation:
The forces that drive metamorphism are changes in pressure and temperature. When a pre-existing rock is exposed to heat and/or pressure, it undergoes a recrystallization process, resulting in the formation of new minerals and changes in the rock's texture. Pressure can increase with depth in the Earth, especially during tectonic plate collisions, while heat can be derived from a magma chamber or the geothermal gradient. By altering the physical and chemical conditions of the rock, metamorphism leads to the formation of metamorphic rocks.