1. ROCKS

2. What is a Rock?
Naturally-occurring mixtures of minerals, mineraloids, glass or organic matter.

3. What is a Rock?
Rocks are divided into 3 groups based on how they were formed:
IGNEOUS
SEDIMENTARY
METAMORPHIC

4. What is the difference between a rock and a mineral?
Rocks are made up of ONE or MORE minerals.

5. Once a rock is formed, does it stay the same rock forever?
NO!

6. Rocks are continually changed by many processes, such as weathering, erosion, compaction, cementation, melting, and cooling
Rocks can change to and from the three types

7. What is the process through which rocks change?
The Rock Cycle—earth materials change back and forth among the different types of rocks

8. IGNEOUS METAMORPHIC SEDIMENTARY
Weathering, Erosion, Compaction, Cementation
Recrystallization
Melting, Solidification
Melting, Solidification
Recrystallization
SEDIMENTARY
METAMORPHIC
Weathering, Erosion, Compaction, Cementation

9. The core, mantle, & crust are one giant rock recycling machine

10. “Ignis” = Latin for “fire”
Igneous Rocks
“Ignis” = Latin for “fire”
Formed from the cooling of either magma or lava
The most abundant type of rock
Classified according to their origin and composition

12. ORIGIN— Where rocks are formed
Below ground = intrusive rock, made from cooling of magma
Usually have coarse (large) crystal grains because they cooled slowly.

13. Above ground = extrusive igneous rock, formed from cooling of lava
Usually have fine (small) or even NO crystals because they cooled fast!

14. #7 Granite: Intrusive or Extrusive? Why?
Intrusive! It is coarse-grained with large crystals, thus cooling slowly.

15. #1: Obsidian: Intrusive or Extrusive? Why?
Extrusive! It is fine-grained, no crystals and glassy luster indicate fast rate of cooling.

16. #3 Scoria: Intrusive or Extrusive? Why?
Extrusive! Air pockets indicate fast rate of cooling, exposure to air.

17. #4 Basalt: Intrusive or Extrusive? Why?
Extrusive! It is fine-grained with very small crystallization.

18. Practice Classifying Igneous Rocks as intrusive or extrusive—
Take out & classify these rocks from your kits. Examine the texture and determine if they are coarse-grained (large crystals) or fine-grained (small or no crystals). Make two piles!

19. Mafic (Basaltic) Igneous Rocks Made from lava/magma that is low in silicate minerals, rich in iron and magnesium. Rocks are dark-colored.

20. Felsic Igneous Rocks—made from magma/lava high in silica and oxygen (like the mineral, quartz). Rocks are light-colored.

21. #4: Basalt
Mafic! High mineral content of olivine and hornblende; both heavy, dense minerals.

22. #2: Pumice
Felsic! Light color indicates silicate minerals.

23. Practice Classifying Igneous Rocks according to their composition: Felsic or Mafic? Make two piles!

24. #10: Diorite: Felsic or Mafic?
Considered “Intermediate” because it has almost equal amounts of plagioclase (gray feldspar) and hornblende!

25. Sedimentary Rocks
Formed from sediments that include rock fragments, mineral grains, animal & plant remains
Sediments erode from bigger rocks due to mechanical or chemical weathering.

26. Sedimentary Rocks
These sediments are moved by wind, water, ice or gravity.
Sediments lay down on Earth’s surface in a process called “deposition”.
Sediments compact and
cement together or
precipitate (make solid)
out of a solution

27. The heavy sediments press down on the layers beneath
Compaction
The heavy sediments press down on the layers beneath

28. Cementation
Dissolved minerals flow between the particles and cement them together

29. How were most of the sedimentary rocks in Ohio deposited?
Continental glacier
Ancient seas

30. How can sedimentary layers help us understand the age of fossils?
As sedimentary rocks are deposited, they form horizontal layers
Scientists know that the layers on top (and the fossils in the top layer) are YOUNGER than the fossils in lower layers.

32. Types of Sedimentary Rocks:
Clastic: made of broken pieces of other rocks or shells cemented together
Coquina
Conglomerate
Sandstone
Breccia

33. Types of Sedimentary Rocks:
Chemical—minerals dissolved in lakes, seas, or underground water

34. Examples
Limestone made when calcite mineral precipitates from sea water
Rock Salt—made from evaporation of sea waters

35. Types of Sedimentary Rocks:
Organic—remains of plants or animals are deposited in thick layers
Examples:
Fossil rich limestone is made from the shells of ocean animals; used to make chalk
Shale and coal

36. Clastic, Chemical, or Organic?
#16
Conglomerate
CLASTIC

37. Clastic, Chemical or Organic?
Bituminous Shale (black because of the remains of plants)
#20
CLASTIC AND ORGANIC

38. Clastic, Chemical, or Organic?
#23
Travertine
CHEMICAL

39. Separate your sedimentary rocks
by making two piles,
one pile of
Clastic rocks,
and the other pile of
Chemical rocks!

40. Rocks that have changed due to intense temperature and pressure
Metamorphic Rocks
Rocks that have changed due to intense temperature and pressure
“Meta” means “change” and morphosis means “form” in Greek
Igneous, sedimentary and other metamorphic rocks can change to become metamorphic rocks

41. Regional Metamorphism
Tectonic plates push into each other above and below the surface of the Earth
Enormous pressure on rock that is buried under other rock formations; makes foliated (banded) rock.

42. Contact Metamorphism
Heat, but not enough to melt the rock, comes from contact with magma bodies and re-crystallizes minerals;
Makes non-foliated rock.
Note the white marble on the mountainside.

43. How are metamorphic rocks classified?
Foliated—mineral grains are flattened and line up in parallel bands
Example: gneiss formed from rearrangement of minerals in granite into bands

44. How are metamorphic rocks classified?
Non-Foliated—No bands are formed
Minerals break bonds and re-crystallize
Quartzite
Below: marble formed from limestone

45. Separate your metamorphic rocks into two piles,
one pile of foliated rock caused by
regional metamorphism,
and the other pile of non-foliated rock caused by
contact metamorphism!

46. Where do metamorphic rocks usually form?
Where magma intrudes relatively cool rock
Near colliding plates (near mountain ranges)
Places that are covered miles thick with other rock causing pressure
When hot water intrudes rock
Where a meteorite strikes Earth (rare)
Where lightning bolts strike rocks (rare)