Here's how it works:
* Heat and Pressure: The key ingredients for metamorphism are intense heat and pressure. This can come from various sources:
* Burial: As layers of sediment accumulate, the weight of the overlying layers creates pressure.
* Plate Tectonics: When tectonic plates collide, the immense pressure and friction generate heat.
* Magma Intrusion: When molten rock (magma) pushes through existing rocks, it releases heat that can transform surrounding sedimentary layers.
* Recrystallization: The heat and pressure cause the minerals in the sedimentary rock to become unstable. They rearrange their crystal structure, forming new minerals. This process is called recrystallization.
* Texture Changes: The pressure also causes the rock to deform, often aligning the newly formed crystals in a specific direction, creating a foliated texture (like layers) in some metamorphic rocks.
Examples of Metamorphic Rocks:
* Marble: Formed from limestone (sedimentary rock) under heat and pressure.
* Slate: Formed from shale (sedimentary rock) under moderate heat and pressure.
* Quartzite: Formed from sandstone (sedimentary rock) under intense heat and pressure.
Important Note: Metamorphism does not melt the rock completely. If the rock melts, it becomes magma and will solidify into igneous rock. Metamorphism is a process of solid-state transformation.
