Metamorphic rocks are formed deep within the Earth's crust as a result of intense heat and pressure. These conditions cause the minerals in pre-existing rocks, such as igneous and sedimentary rocks, to recrystallize and change into new mineral forms. The heat and pressure can be caused by a variety of different processes, including tectonic activity, volcanic activity, and the movement of hot fluids through rocks.One way that metamorphic rocks can be formed is through regional metamorphism. This occurs when large areas of rock are subjected to high temperatures and pressures over a wide area. This can happen when two tectonic plates collide and one plate is pushed beneath the other, causing the rocks to be heated and compressed. An example of this is the rock found in the Himalayan mountain range, which was formed by the collision of the Indian and Eurasian tectonic plates.Another way that metamorphic rocks can be formed is through contact metamorphism. This occurs when rocks are heated by contact with an intruding magma chamber or lava flow. The heat causes the surrounding rocks to change, creating a zone of metamorphism around the intrusion. An example of this is the rock found in the area around a volcano, which has been heated by the nearby magma.A third way that metamorphic rocks can be formed is through hydrothermal metamorphism. This occurs when hot fluids, such as water or mineral-rich fluids, move through the rocks and cause them to change. The fluids can carry dissolved minerals that will precipitate out and form new minerals in the rock. An example of this is the rock found in hot springs, which has been changed by the hot fluids that flow through it.Overall, metamorphic rocks are formed deep within the Earth's crust as a result of intense heat and pressure. The specific process of formation can vary, including regional metamorphism, contact metamorphism and hydrothermal metamorphism. These rocks are formed by the recrystallization of pre-existing rocks and have unique physical and chemical properties. They are widely used in construction, as they are hard and durable.