These are formed when either igneous or sedimentary rocks are changed. Heat and/or pressure will cause the elements in the original rock to react and re-form. Metamorphic rocks are highly ...

Over time, the layers are compressed and glued together.Metamorphic rocks are formed from other rocks, igneous or sedimentary, which are heated and compressed underground.Igneous rocks are formed ...

It depends on what the rocks are made of – and that’s related to how they were formed. There are three main rock types: igneous, sedimentary and metamorphic. These rocks are made of minerals ...