1. Sedimentary Rocks!

2. Formation of Sedimentary Rocks
It’s all part of the Rock Cycle, baby!

3. So, how are these things made anyway?
Weathering
Erosion
Deposition
Lithification

4. Weathering
Can result in particles as big as boulders or so small they require a microscope to see them!
Chemical Weathering: Minerals are dissolved or otherwise chemically changed.
Physical Weathering: Minerals remain chemically unchanged

5. Physical Weathering
Hydraulic Action
Frost weathering
Pressure Release
Rocks are broken down, but not changed. Heat, water, ice, or pressure may cause physical weathering.
Heat and cooling may cause rock to expand and contract.
Ice may cause frost weathering.
Pressure can cause underlying rocks to expand and break the rocks above them.
Water can enter rock very quickly and cause it to expand and break.

6. Chemical Weathering
Chemical weathering changes the composition of rocks.
Water is often involved, interacting with minerals to cause chemical reactions.
This process is gradual and ongoing.

7. Erosion Erosion is the removal and transport of sediment.
There are four main agents of erosion: wind, moving water, gravity, and glaciers.
You can see erosion all around you!

8. Wind Erosion Wind erosion occurs almost always in deserts.
Sand dunes are formed by wind erosion.

9. Water Erosion
The energy of water waves, along with the chemical content of the water, erodes the coastline.
Erosion of sand is easy for water waves to do.
River erosion is what caused the Grand Canyon to form!

10. Gravity Erosion This is the movement of sediment down a slope.
Also called “mass wasting.”
Some types are creep, slides, flows, topples, and falls.

11. Glacial Erosion
More powerful than erosion caused by moving water, but not as common.
A glaciers can break off pieces of rocks and carry them with it as it moves (plucking), or scoop rock up like a bulldozer and carry it along (abrasion).

12. So, weathering and erosion are the same thing, right?
WRONG!!!
Weathering loosens particles, erosion transports them.
IN OTHER WORDS… when something is weathered it is broken down into smaller pieces, when it is eroded it moves away.
SO….. Weathering decomposes rocks, but as soon as it is transported, we call it erosion!

13. So, what happens after that?
Deposition…
when the transported sediments are deposited on the ground or sink to the bottom of a body of water.

14. …Okay, but how does all of that sediment become a ROCK?
Lithification!
Occurs in 2 main steps:
compaction and cementation.

15. Compaction and Cementation
Volume and spaces between sediment are decreased
Because of the weight of sediments above
Cementation –
Sediments are glued together by minerals deposited from water

16. Types of Sedimentary Rock
Sedimentary rock can be classified by HOW it forms
Chemical
Organic
Clastic

17. Chemical Sedimentary Rock
Formed from minerals that were once dissolved in water
One reason this happens… evaporation
Ex – halite Bonneville Salt Flats, Utah

18. Organic Sedimentary Rock
Formed from the remains of living things
Remains are compacted
and cemented to form
sedimentary rock
Also called bioclastic

19. Organic Sedimentary Rock
Coal –
plant remains
Limestone –
shell remains of marine animals

20. Clastic Sedimentary Rock
Formed from fragments of preexisting rocks
1. Large fragments cemented together by fine particles
Ex – conglomerate Ex – breccia

21. Clastic Sedimentary Rock
2. Sand-sized grains cemented together
Ex – sandstone

22. Clastic Sedimentary Rock
3. Clay-sized particles cemented together
Ex - shale

23. Clastic Characteristics
Sorting
Tendency for air or water to separate sediments by size
Well Sorted
Poorly Sorted

24. Clastic Characteristics
Angularity
Particles that first break from a source are angular
Particles that have moved long distances are round & smooth

25. Sedimentary Features Stratification Layering of sedimentary rock
Layers are called beds
Cross-beds
Slanting layers that form within beds

26. Sedimentary Features Ripple Marks
Caused by the action of wind or water on sand
Mud Cracks
Occur when a flooded area, like a lake bed, dries and the mud shrinks
Fossils
Traces of ancient plants and animals