1. Bellringer
Complete #5 on page 70 in your book. You do not have to write the question.

2. Sedimentary Rocks
Science 7
Study Pack #4

3. Today’s Goals… I can explain how sedimentary rocks form from sediments
I can classify sedimentary rocks as detrital, chemical, or organic in origin.

4. Sedimentary Rocks
75% of rocks exposed at the surface of the earth are sedimentary
Sediments are loose materials such as:
rock fragments
mineral grains
remains of organisms
bits of shell
Carried to new locations by wind, water, ice, or gravity

5. Sedimentary Rocks
Sediments come from already existing rocks that are weathered and eroded
Rock forms when sediments are pressed and cemented together

6. Sedimentary Rocks Form as layers Older layers at the bottom
They were deposited first

7. Sedimentary Rocks Classified by their composition and how they form
Detrital
Chemical
Organic

8. Detrital Sedimentary Rocks
Made from pieces of other rocks
Rock is first weathered (broken up) and then eroded (carried away)
Sediments are then deposited (laid down)
Pressure from layers of rock cause the pieces to become stuck together or compacted

9. Detrital Sedimentary Rock
Sometimes water and minerals flow between sediments and act as a natural cement to hold the sediments together
Examples:
Conglomerate: rounded sediments
Breccia: sharp edged sediments

10. Conglomerate and Breccia
Animation

11. Chemical Sedimentary Rocks
Form when dissolved minerals come out of a solution
Imagine a glass of salt water
Examples: Limestone, rock salt (Halite)
Many uses – page 75

12. Organic Sedimentary Rocks
Made up of the remains of once living things
May contain fossils
Examples: chalk, coal, some limestone

13. Coal
Forms when pieces of dead plants are buried under sediments in swamps
Compacted for millions of years
Most coal formed during the Carboniferous period