1. Metamorphic rocks Vocabulary to know:
Metamorphism-regional, contact, hydrothermal
Recrystallization
Foliated
Non-foliated
Porphyroblast
Rock Cycle
Metamorphic rocks

2. Heat and Pressure Change Rocks
Metamorphism- the process in which an existing rock is changed by heat, pressure or both

3. Metamorphic rock
The original sedimentary rock or igneous rock is called the PARENT ROCK
Limestone is the parent rock of MARBLE (a metamorphic rock)

4. Metamorphic rock
Rocks DO NOT melt when they undergo metamorphism

5. Metamorphic rock
Recrystallization- when heat and pressure break the bonds that join atoms in minerals and these atoms join together differently (new bonds)
Crystals can grow larger
Atoms can combine in different ways

6. Metamorphic rock
Changes can occur over large and small areas

7. Changes Over Large Areas
Temperature AND pressure is HIGH
Regions where large blocks of rocks are pressing together and pushing up mountain ranges. Can affect an area hundreds of km wide and tens of km deep

8. Changes Over Small Areas
Mainly due to HIGH TEMPERATURE not pressure
Magma can push into rocks underground, or surface rock can be covered by lava flow
Rocks get BAKED not squeezed
Rocks can also be changed by earthquakes (pressure can cause rocks to grind together)

9. Types of Metamorphism
Different combinations of temperature and pressure result in different types of metamorphism
Regional metamorphism
Contact metamorphism
Hydrothermal Metamorphism

10. Regional Metamorphism
When temperature and pressure effect LARGE regions of Earth’s crust
Can be low, intermediate or high grade
The grade reflects the relative temperature and pressure (low grade being low temps and pressures)

11. Contact Metamorphism
when molten rocks come in contact with solid rock.
High temperature and moderate to low pressure
Results in large scale mineral changes with little deformation

12. Hydrothermal Metamorphism
When very hot water reacts with rock and alters its chemistry and mineralogy
Fluids can dissolve, break down or deposit minerals
Common around active volcanoes

13. Metamorphic rock
Most metamorphic rock develop bands of minerals

14. FOLIATION
An arrangement of minerals in flat or parallel bands

15. Foliated rocks
Develops when minerals flatten or line up in bands or wavy layers.

16. Foliated rocks Low levels of metamorphism make extremely THIN bands
Higher temperatures and pressure cause the mineral mica to grow and makes the rock look SHINY
Even higher levels of metamorphism causes the minerals in the rock to separate into light and dark bands

17. Foliated rocks
SLATE

18. Foliated rocks
PHYLLITE

19. Foliated rocks
SCHIST

20. Foliated rocks
GNEISS

21. Nonfoliated rocks Does NOT split into layers
This can happen in two ways:
Rock made of mainly ONE type or mineral such as marble
Has NOT been subjected to high PRESSURE such as hornfels

22. Nonfoliated rocks
Quartzite

23. Nonfoliated rocks
Marble

24. Porphyroblasts
Large crystals that form in solid rock by the reorganization of atoms during metamorphism
Found in areas of both contact and regional metamorphism

25. The Rock Cycle
Rocks change but the change usually occurs over a huge span of time-thousands to millions of years

26. The Rock Cycle
The continuous changing and remaking of rocks

27. The Rock Cycle

28. The Rock Cycle
Lets try to explain the rock cycle as a class!

29. The Rock Cycle

30. ROCK TYPES
Rocks are classified by how they are formed.
The three types of rocks we earned about in this unit: igneous, sedimentary and metamorphic rocks.