Formation and Characteristics
 “Meta” means
change (Greek)
 “Morph” means form (Greek)
A
rock that has been changed from its
original form (parent rock) by heat,
pressure, and fluid activity into a new
form (daughter rock).
 Contact
– caused by proximity to igneous
activity. Heat causes minerals to
recrystallize but not melt.
 Dynamic
– associated with faults and
earthquake zones
 Regional
– Caused by tremendous
pressures associated with plate tectonics.
Deep burial.
Progression of Metamorphism
Start with a shale and then hit
it with heat and pressure!
More
Heat
&
Pressure
Rock Name
Rock Type
Grade of
Metamorphism
Shale
Sedimentary
-----
Slate
Metamorphic
Low
Phyllite
Metamorphic
Low/Intermediate
Schist
Metamorphic
Intermediate/High
Gneiss
Metamorphic
High
Molten Rock
Cools into
Igneous Rock
-----
Shale
(Sedimentary Rock)
Heat
&
Pressure
Slate
(Metamorphic Rock)
Slate
(Metamorphic Rock)
Heat
&
Pressure
Phyllite
(Metamorphic Rock)
Phyllite
(Metamorphic Rock)
Heat
&
Pressure
Schist
(Metamorphic Rock)
… you end up with something
that is really Gneiss!
 Foliated
• “Folios” means page, or leaf-like
• Rock has distinct layers
 Often not smooth layers like sedimentary rock
• Formed under direct pressure (ex. Pushing
down)
 Non-foliated
• No distinct layers
• Often a massive crystalline structure
• Formed under uniform pressure (all directions)
Foliated Texture
Non-foliated Rocks
• Marble:
- metamorphosed
limestone
Quartzite:
•• Quartzite:
-- metamorphosed
metamorphosed
quartz sandstone
sandstone
quartz
 Rocks
whose form is changed by
temperature and pressure.
 3 different types
• Contact
• Dynamic
• Regional
 2 Textures
• Foliated
• Non-foliated
 More temperature
changes
and pressure = more