1. Rock Groups

2. What is a rock?
A coherent, naturally occurring solid, consisting of an aggregate of minerals!

3. These are called clastic rocks
What holds rock together?
Natural cement – mineral material that precipitates from water and fills in gaps
These are called clastic rocks
Sandstone is an example of clastic rocks

4. These are called crystalline rocks
2. Minerals interlock with one another like pieces of a jigsaw puzzle
These are called crystalline rocks
Picture of granite as a crystalline rock.

7. Rock Classification
By the end of the 18th century, most geologists accepted the genetic scheme for classifying rocks.
Rock classification focuses on the origin (genesis) of rocks!

8. 3 Basic Groups:
1) Igneous
2) Sedimentary
3) Metamorphic

9. Each group contains many different individual rock types, distinguished from one another by physical characteristics:
1. Grain size

10. 2. Composition
3. Texture

11. 4. Layering