A metamorphic grade takes into account only the change in
temperature while a metamorphic facies is more specific by showing
the change in temperature in relation to the change in pressure and
depth. There are three grades: low (250°C-400°C), intermediate
(400°C-600°C) and high (above 600°C). Although there are many
facies, the major ones are zeolite, hornfels, greenschist,
amphibolite, blueschist, eclogite, and granulite. This allows for
geologist to easily locate where a metamorphic rock was formed.