1. Sedimentary Rocks are Formed from Earlier Rocks
3.3 Notes
Sedimentary Rocks are Formed from Earlier Rocks

2. What determines how rock pieces settle in water?
Think About…
What determines how rock pieces settle in water?
If I pour sand and rocks into a jar, then _____ will sink to the bottom first because _________.

3. Some Rocks Form from Rock Particles
If sand grains on a beach become cemented together, they form a sedimentary rock called sandstone.

4. Some Rocks Form from Rock Particles
MOST sedimentary rock forms from loose material getting pressed together and cemented into rock.

5. Some Rocks Form from Rock Particles
Sedimentary rock takes its name from the word sediment, which means “something that settles.”

6. Some Rocks Form from Rock Particles
Sediments are materials that settle out of water or air.

7. Some Rocks Form from Rock Particles
Pieces of plant and animal remains can make up sediments in addition to loose rocks and minerals.

8. Forming and Transporting Rock Particles
Sediments can range in size from boulders to sand.

9. Forming and Transporting Rock Particles
Rain washes away tiny rock pieces as it flows downhill.
The water carries these particles to rivers which eventually empty into lakes or oceans.

10. Forming and Transporting Rock Particles
Wind can also pick up sand and rock dust and carry them to distant places.

11. Forming Loose Sediments into Rocks
As water or wind deposits stuff in layers, the layers eventually get buried by more layers.
The layers on top press down on the layers underneath.

12. Forming Loose Sediments into Rocks
Sometimes this pressure is enough to turn the layers into rock.
Other times, minerals crystallize between the layers that cement them together.

13. Some Rocks Form from Plants or Shells
Processes similar to the ones that produce sedimentary rocks from rock particles also produce rocks from shells or plant remains (fossils).

14. Coal
If you look at a piece of coal through a magnifying glass, you may see shapes of wood or leaves.

15. Coal is made up of remains of plants.
That is why coal is called a “fossil fuel.”
The coal we use today started forming millions of years ago.

16. Limestone
Limestone is made of carbonate minerals such as calcite, found in organisms with shells.

17. Eventually, this sediment is formed into limestone.
When the organisms die, their shells settle on the ocean floor as sediment.
Eventually, this sediment is formed into limestone.

18. Some Rocks Form When Dissolved Minerals Re-Form from Water
Some sedimentary rocks are made up of minerals that crystallized as water dried up.

19. Some Rocks Form When Dissolved Minerals Re-Form from Water
As water moves through limestone, some of the rock dissolves.
This can eventually form huge open spaces (caves) in the rock.

20. Some Rocks Form When Dissolved Minerals Re-Form from Water
As the water flows and drips through a cave, some of it evaporates, making many odd and beautiful shapes.

21. Some Rocks Form When Dissolved Minerals Re-Form from Water
Sometimes minerals crystallize along the edge of lakes and oceans when the water evaporates.
This is how salt and gypsum are both formed.

22. Sedimentary Rocks Show the Action of Wind and Water
Sedimentary rocks are laid down in layers, with the oldest layers on the bottom.

23. Sedimentary Rocks Show the Action of Wind and Water
Geologists can study these layers to know what Earth was like in the past.

24. Sedimentary Rocks Show the Action of Wind and Water
The sediments also tell geologists what wind and water erosion were like in the past.

25. Sedimentary Rocks Show the Action of Wind and Water
A rock layer with large particles on the bottom and small particles on the top indicate that the water carrying the sediment was slowing down.

26. Sedimentary Rocks Show the Action of Wind and Water
This kind of rock layer is often created by a flood.

27. Sedimentary Rocks Show the Action of Wind and Water
Sedimentary rocks also give information about the directions in which long ago wind or water currents were moving when sediments settled from them.

28. Sedimentary Rocks Show the Action of Wind and Water
Rocks made of clay or silt that have cracks indicate they were formed during a wet period followed by a dry period.

29. Pieces of rock can settle from water and get cemented into
Review
Pieces of rock can settle from water and get cemented into
Metamorphic rock
Sedimentary rock
Igneous rock
Extrusive rock

30. Review
2. Rock salt is an example of a sedimentary rock that develops from dissolved minerals as
Water evaporates
Magma cools
Sediments break down
Sand settles in water