1. Rocks and the Rock Cycle
It Rocks!
Rocks and the Rock Cycle

2. Just what are rocks?
A rock is a mixture of minerals, rock fragments, volcanic glass, organic matter, or other natural materials.
What do you see in this sample of pink granite?

3. What is the difference between a rock & a mineral?
Minerals are solid, naturally occurring, inorganic, have a fixed composition and are made of one or more elements.
Rocks are made of one or more minerals.

4. Let’s Compare… Solid Made of elements Must be inorganic
Can be made from organic materials
Must be inorganic
Solid
Can be made of lava/ magma
Mixtures made of minerals
Made of elements or compounds and must be chemically bonded
Naturally occurring
Have crystals
Can be man made
Can be formed from solutions

5. Rock Classifications
Igneous
Sedimentary
Metamorphic

6. Igneous Rock Igneous is Greek and means ‘born of fire’
Igneous rock forms when magma, hot molten rock, cools and hardens
Igneous rock can be intrusive or extrusive

7. Intrusive Igneous Rock
Formed from magma cooled below the Earth’s surface
Cools very slowly
Forms mineral grains large enough to see with the unaided eye

8. Extrusive Igneous Rock
Formed as lava cools on the surface of the Earth
Cools quickly
Exposed to air and water which can result in holes in the rock material
Forms very fine (small) mineral grains.

9. Extrusive Igneous Rock
Includes Volcanic Glass
Lave cools very very quickly
Few or no minerals grains form
Atoms are not arranged in an orderly pattern

10. Sedimentary Rock
Forms when sediments are pressed and cemented together
Forms when minerals form from solutions
Often form layers
If undisturbed by nature, the oldest and first layer is the bottom layer

11. Sedimentary Rock
Sediments are loose rock fragments, minerals grains, and bits of shell that have been moved by the wind, water, ice or gravity.
Sediments form from the processes of weathering and erosion
Compaction – occurs when pressure on the uppers layers of the sedimentary rock pushes down on the lower layers.
Cementation – the process by which water and dissolved minerals move through open spaces and form a glue-like substance

12. Metamorphic Rock Metamorphosis – to change
Rocks that have changed their chemical composition due to the presence of extreme heat and pressure or
Rocks that have been subjected to hot watery fluids

13. Metamorphic Rock
Can form from igneous, sedimentary or other metamorphic rock
Can be foliated - mineral grains appear in parallel layers
Can be nonfoliated – mineral grains do not align in layers

14. The What?...The Rock Cycle
To show how rocks slowly change through time, scientists have created a model called the rock cycle.
It shows the processes that form and change rocks.
The rock cycle shows the three classifications of rock— igneous, metamorphic, and sedimentary—and the processes that form them.

15. The Rock Cycle explains how Rocks and Natural Processes are related
weathering
Sedimentary
Metamorphic
Is the rock cycle really this simple, neat and colorful?
(NO)
Created October 2, 2000, revised September 2001
melting
pressure, heat
Igneous

16. What is the law(principle) of conservation of matter?
Law of conservation of matter states that matter cannot be created or destroyed.
The changes that take place in the rock cycle never destroy or create matter.
The elements are just redistributed in other forms.

17. Let’s Have Some Fun!!

18. More Fun with the Rock Cycle
(Study Jams – really great site)

19. Prepared just for YOU, my 6th Grade Earth Science classes!
Ms. Houston
Austin Road Middle School