1. Notes
Sedimentary Rocks

2. Think About
What do you think would settle to the bottom of a body of water faster, rocks or sand? Why?

3. Clastic Sedimentary Rock
MOST sedimentary rock forms from sediment getting pressed together and cemented into rock.

4. Clastic Sedimentary Rock
Sedimentary rock takes its name from the word sediment, which means “something that settles.”

5. Clastic Sedimentary Rock
Sediments are loose materials that settle out of water or air.

6. Clastic Sedimentary Rock
Sediments can range in size from boulders to sand.

7. Clastic Sedimentary Rock
Rain washes away tiny rock pieces as it flows downhill.
The water carries these particles to rivers which eventually empty into lakes or oceans.

8. Clastic Sedimentary Rock
Wind can also pick up sand and rock dust and carry them far away.

9. Clastic Sedimentary Rock
As water or wind makes layers of sediment, the layers eventually get buried by more layers.
The layers on top press down on the layers underneath.

10. Clastic Sedimentary Rock
Sometimes this pressure alone is enough to turn the layers into rock.
Other times, minerals also crystallize between the layers and cement them together.

11. Clastic Sedimentary Rock
Sedimentary rock formed from loose rock particles is called clastic sedimentary rock.

12. Clastic Sedimentary Rock
If sand grains on a beach become cemented together, they form a sedimentary rock called sandstone.

13. Organic Sedimentary Rock
Small pieces of plant and animal remains can also be found in sediment.

14. Organic Sedimentary Rock
Sedimentary rocks can be made from broken down shells or plant remains (fossils).

15. Organic Sedimentary Rock
If you look at a piece of coal, you can sometimes see shapes of wood or leaves.

16. Organic Sedimentary Rock
Coal is made up of plant remains.
That is why coal is called a “fossil fuel.”
The coal we use today started forming millions of years ago.

17. Organic Sedimentary Rock
Limestone is made of minerals such as calcite, found in organisms with shells.

18. Organic Sedimentary Rock
When shelled organisms die, their shells pile up and break down on the ocean floor.
Eventually, this sediment is formed into limestone.

19. Organic Sedimentary Rock
Sedimentary rock formed from fossils is called organic sedimentary rock.

20. Chemical Sedimentary Rock
Some sedimentary rocks are made up of minerals that crystallize as water evaporates.

21. Chemical Sedimentary Rock
As water moves through limestone, some of the rock dissolves.
This can form open spaces (caves) in the rock.

22. Chemical Sedimentary Rock
As the water flows and drips through a cave, some of it evaporates, making many odd and beautiful shapes.

23. Chemical Sedimentary Rock
Sometimes minerals crystallize along the edge of lakes and oceans when the water evaporates.
This is how salt and gypsum are both formed.

24. Chemical Sedimentary Rock
Sedimentary rock formed by the evaporation of water is called chemical sedimentary rock.

25. Sedimentary Rock Formations
Sedimentary rocks are formed in layers, with the oldest layers on the bottom.

26. Sedimentary Rock Formations
Geologists can study these layers to know what Earth was like in the past.

27. Sedimentary Rock Formations
The sediments can tell geologists what wind and water erosion were like in the past.

28. Sedimentary Rock Formations
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.

29. Sedimentary Rock Formations
This kind of rock layer is often created by a flood.

30. Sedimentary Rock Formations
Rocks can also show the direction wind or water currents were moving when sediments settled from them.

31. Sedimentary Rock Formations
Rocks made of clay or silt with cracks indicate they were formed during a wet period followed by a dry period.

32. 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

33. 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

34. Review
3. When hiking outdoors you notice an object and pick it up. You observe the following characteristics: the object is black in color, has a rough texture, dull in luster, and contains organic matter. What is the object you are holding?
Obsidian
Quartz
Coal
Magnetite