The grade of metamorphism is usually studied in the metamorphic type of rocks where the rocks are formed due to the high pressure and temperature condition. These rocks are formed in a sequence from a lower grade to a higher grade. Here the low-grade rocks gradually change to more hard and resistant rock when subjected to extreme pressure-temperature conditions.
In the above, there are 3 metamorphic rock names gives, which can be arranged from a lower grade to higher grade. Slate is a low-grade metamorphic rock that changes into Phyllite, another medium-grained metamorphic rock. This Phyllite again alters to Schist under extreme pressure-temperature conditions.
