Here's why:
* Regional Metamorphism: This type of metamorphism occurs over large areas, usually due to the immense pressure and heat generated by tectonic plate collisions.
* Low Grade: This refers to the initial stages of metamorphism, where temperatures and pressures are relatively low.
* Slate: This fine-grained metamorphic rock forms from the transformation of shale, a sedimentary rock. The pressure and heat cause the clay minerals in shale to recrystallize, resulting in a rock that is easily cleaved into thin, flat sheets.
As the metamorphic grade increases, slate can be further transformed into other metamorphic rocks like phyllite, schist, and gneiss.
