1. Sedimentary, Igneous, and Metamorphic
Rocks
Sedimentary, Igneous, and Metamorphic

2. There are 3 basic types of rocks – sedimentary, igneous and metamorphic. Rocks are made of one or more kinds of minerals and/or organic matter.
Sedimentary rocks form when sediments are lithified (converted into solid rock.)
Igneous – form when magma or lava cools into solid rock
Metamorphic – formed when rock changes shape or composition under intense heat and/or pressure without melting. If it melts, it becomes igneous.
Throughout this entire presentation, only the most common and easily identifiable rocks are discussed.

3. 3 Types of Sedimentary Rocks
Clastic
Chemical
Organic
The sedimentary section is broken into 5 sections: Siliciclastic sediments, Chemically precipitated sediments, Organic sediments, Diagenesis and Sedimentary environments.

4. Clastic Sedimentary Rock
Sediments form when rocks are weathered and eroded
Sediments are moved by wind, glaciers and water
Most clastic sediments are deposited in the ocean
Siliciclastic means silica fragments. These particles are made mostly of silica (oxygen and silicon).

5. Clastic Sedimentary Rock
Sediments are converted into solid sedimentary rock by the processes of compaction and cementation.
Siliciclastic means silica fragments. These particles are made mostly of silica (oxygen and silicon).

6. Clastic Sedimentary Rock
Compaction & Cementation
Siliciclastic means silica fragments. These particles are made mostly of silica (oxygen and silicon).

7. Clastic Sedimentary Rock
Compaction & Cementation
Siliciclastic means silica fragments. These particles are made mostly of silica (oxygen and silicon).

8. Clastic Sedimentary Rock
Compaction occurs when the weight of overlying materials compresses the deeper sediments.
Cementation occurs when soluble cementing materials, such as calcite, silica, and iron oxide, are precipitated onto sediment grains, fill open spaces, and join the particles.
Siliciclastic means silica fragments. These particles are made mostly of silica (oxygen and silicon).

9. Clastic Sedimentary Rock
Particle (clast) size is key to type of rock
Gravel is > 2 mm
Sand is 1/16 mm to 2 mm
Mud is < 1/16 mm
Clay is < 4 um
Silt is > 4 um
Basic classification of siliciclastic sediments is based upon sediment size. The um measurement here is micrometers (10-6 m)

10. Sandstone
Sandstone is probably the most common type of siliciclastic rock. When you look at sandstone, you can see the small sand-sized grains with the naked eye. Many rocks have layers visible in them, but some do not.

11. Conglomerate
Conglomerate is made of different sized particles from gravel down to mud. These are typically deposited in river bottoms and then buried and lithified over time.

12. Shale
Shale is made of mud or clay size particles – you need a hand-lens to see the grains. Shale is laid down in layers and the rocks split along those layers fairly easily. Some oil shale deposits have enough oil in them that it is quickly becoming a possibility to mine these rocks, crush them and remove the oil for profit.

13. Chemical Sedimentary Rock
Chemical sedimentary rocks are made of mineral crystals that formed from chemicals dissolved in water.
The water in the oceans, lakes, and underground is often full of dissolved minerals and other elements.
Chemically precipitated sediments include limestone, halite, gypsum, diatomaceous earth and dolomite. These all form when ions (charged atoms) that are released during chemical weathering are carried away in solution.
The ocean is not becoming saltier, so new minerals are precipitated out to balance the continual influx. Rocks form at the same rate that the ions reach the ocean.
Chemical precipitates include inorganic (no living matter) and organic (include living matter).
The ultimate source for the CO3 is CO2 from the atmosphere. The ocean is the biggest sink for CO2, which is then tied up in shells and other ocean animals.

14. Chemical Sedimentary Rock
When water is so full of elements that not all will fit, some are not able to remain dissolved.
They come out of solution, or precipitate, forming solid mineral crystals.
Precipitation is the opposite of dissolving.
Chemically precipitated sediments include limestone, halite, gypsum, diatomaceous earth and dolomite. These all form when ions (charged atoms) that are released during chemical weathering are carried away in solution.
The ocean is not becoming saltier, so new minerals are precipitated out to balance the continual influx. Rocks form at the same rate that the ions reach the ocean.
Chemical precipitates include inorganic (no living matter) and organic (include living matter).
The ultimate source for the CO3 is CO2 from the atmosphere. The ocean is the biggest sink for CO2, which is then tied up in shells and other ocean animals.

15. Chemical Sedimentary Rock
Minerals precipitate when some water has been evaporated or when a chemical reaction occurs.
Evaporation takes only water molecules into the atmosphere so the elements in the remaining liquid water become very concentrated. Eventually, they do not all fit and some precipitate out as mineral.
Chemically precipitated sediments include limestone, halite, gypsum, diatomaceous earth and dolomite. These all form when ions (charged atoms) that are released during chemical weathering are carried away in solution.
The ocean is not becoming saltier, so new minerals are precipitated out to balance the continual influx. Rocks form at the same rate that the ions reach the ocean.
Chemical precipitates include inorganic (no living matter) and organic (include living matter).
The ultimate source for the CO3 is CO2 from the atmosphere. The ocean is the biggest sink for CO2, which is then tied up in shells and other ocean animals.

16. Chemical Sedimentary Rock
Chemically precipitated sediments include limestone, halite, gypsum, diatomaceous earth and dolomite. These all form when ions (charged atoms) that are released during chemical weathering are carried away in solution.
The ocean is not becoming saltier, so new minerals are precipitated out to balance the continual influx. Rocks form at the same rate that the ions reach the ocean.
Chemical precipitates include inorganic (no living matter) and organic (include living matter).
The ultimate source for the CO3 is CO2 from the atmosphere. The ocean is the biggest sink for CO2, which is then tied up in shells and other ocean animals.

17. Halite
Halite is salty – but never have students taste rocks. Much of our rock salt is from halite deposits. As the ocean water evaporates, the salt is left behind.

18. Gypsum
Gypsum comes in many different shapes as seen here. Gypsum roses are the top left picture. The most common gypsum deposits are like the right side pictures. Most of the mined gypsum is crushed and then made in drywall or wallboard.

19. Limestone
Limestone forms when chemical precipitates of calcium carbonate form on the ocean floor. Many times, fossil shells are included in the matrix making for very interesting samples. Limestone bubbles in dilute hydrochloric acid or even vinegar. Vinegar might be smelly, but it’s cheaper and safer for students.

20. Dolomite
Dolomite forms in a similar as limestone but has magnesium in the chemical structure. This makes it non-reactive to acid or vinegar. It also rarely contains fossils.

21. Organic Sedimentary Rock
Coal
Coal: Bituminous & Anthracite
Bituminous
Anthracite
Organic sedimentary rocks form from deposits that are mostly or entirely from plant material. Peat is the first stage of these deposits, which can form into coal over time. It takes millions of years to form coal, so it is not a renewable resource.
Coal comes in different grades – lignite, sub-bituminous, bituminous and anthracite. Lignite is very soft and crumbly, anthracite is very hard. The harder the coal, the longer and hotter it will burn, making it more valuable.
It is NOT true that diamonds come from coal deposits. We get our diamonds from ancient volcanoes – mostly in Africa. It is true that coal and diamonds are made of carbon, which makes them similar, but they don’t form the same way.

22. Organic Sedimentary Rock
Coal
Coal is an organic sedimentary rock that has been altered slightly by being compressed and heated.
It was formed by the rapid burial of large numbers of plants; swamp forest.
Over time the plant material is compacted so much by the weight of the overlying sediment that it is turned in to rock.
Organic sedimentary rocks form from deposits that are mostly or entirely from plant material. Peat is the first stage of these deposits, which can form into coal over time. It takes millions of years to form coal, so it is not a renewable resource.
Coal comes in different grades – lignite, sub-bituminous, bituminous and anthracite. Lignite is very soft and crumbly, anthracite is very hard. The harder the coal, the longer and hotter it will burn, making it more valuable.
It is NOT true that diamonds come from coal deposits. We get our diamonds from ancient volcanoes – mostly in Africa. It is true that coal and diamonds are made of carbon, which makes them similar, but they don’t form the same way.

24. Igneous Rocks Magma is the molten rock material below the surface.
Lower density causes magma to rise toward the surface (compared to the surrounding rock).
Magma at the surface is lava.
Igneous rocks are formed from solidified/cooled magma or lava.
Igneous rocks are made of interlocking crystals

25. Igneous Rock

26. Igneous Rocks
Magma extruded onto the Earth’s surface forms volcanic or extrusive igneous rocks.
Magma that crystallizes within the Earth’s crust forms plutonic or intrusive igneous rock.

27. Extrusive & Intrusive Igneous Rocks
Intrusive- Magma under the surface
Coarse-grained (igneous rock)
Magma cools slowly and large crystals grow over a long period of time
Gabbro, diorite, granite

28. Extrusive & Intrusive Igneous Rocks
Extrusive- Lava at the surface
Fine-grained (igneous rock)
Lava cools very quickly, consequently crystals do not have time to grow and develop
Basalt, andesite, rhyolite, obsidian

29. Igneous Rocks
Molten rock or magma(1,000-1,200 oC), contains chemical elements.
If the magma begins to cool, elements begin to form chemical bonds within the magma and crystals start to develop.

30. Igneous Rocks
Rocks that form from magma or lava cooled from high temperatures tend to contain a lot of iron and magnesium but little silica.
These rocks are called mafic and tend to be dominated by dark colored minerals such as amphibole and pyroxene (Elements: iron & magnesium).

31. Igneous Rocks
When magma cools slowly, minerals that form at cooler temperatures dominate the resulting rock.
These rocks are called felsic and tend to be light colored with minerals such as feldspar and quartz. (Elements: silicon, oxygen, sodium, potassium, & aluminum)

32. Igneous Rocks

33. Igneous Rocks

34. Igneous Rocks Classification of Igneous Rocks -Texture: crystal size
-Color
-Mineral composition

35. Igneous Rocks
Granite
Felsic
Intrusive

36. Igneous Rocks
Rhyolite
Felsic
Extrusive

37. Igneous Rocks
Basalt
Mafic
Extrusive

38. Igneous Rocks
Gabbro
Mafic
Intrusive

39. Igneous Rocks
Andesite
Intermediate
Extrusive

40. Igneous Rocks
Diorite
Intermediate
Intrusive

41. Igneous Rocks Other Igneous Rocks Lava flows
Fragmented magma ejected explosively
Ash plumes
Pyroclastic flows
Cool and solidify very quickly; no minerals develop
Consequently they cannot be mafic, intermediate, or felsic

42. Igneous Rocks
Obsidian
Extrusive

43. Igneous Rocks
Pumice
Extrusive

44. Metamorphic Rocks

45. Metamorphic Rocks
The Greek word meta means “change” and morph meaning “shape”.
Metamorphic rocks were previously either sedimentary or igneous rocks, but they have been subjected to very high temperature and pressure. (Below the surface of the Earth)

46. Metamorphic Rocks
The temperature was not high enough to make the rock melt (Metamorphic changes occur as the rock is in solid-state), but it was high enough to allow some crystals to grow, and for the minerals to begin to re-crystallize and thus form a new rock.
As temperature rises, crystal lattices are broken down and reformed with different combinations of atoms. New minerals are formed.

47. Metamorphic Rocks Regional metamorphism Contact metamorphism
The types of metamorphism
Regional metamorphism
Contact metamorphism
Regional metamorphism
Contact metamorphism

48. Metamorphic Rocks Contact metamorphism
In the case of contact metamorphism heat comes from contact with molten magma.
-This type of metamorphism has a limited and local effect.

49. Metamorphic Rocks Regional metamorphism
When rocks are forced toward the mantle during the formation of a mountain range and/or other tectonic activity, regional metamorphism occurs.
-Large volumes of rock are altered in this way.

50. Metamorphic Rocks
Metamorphism does not take place on the Earth’s surface.
Rocks under the Earth’s surface are under great pressure from overlying rock layers.
Deep burial- as depth increases, in the Earth’s crust, the temperature also increases.
Tectonic forces in the Earth may apply lateral pressure to large volumes of rock.

51. Metamorphic Rocks

52. Metamorphic Rocks

53. Metamorphic Rocks
Metamorphic rocks have been exposed to the surface of the Earth because erosion has striped away overlying rocks.
So, when we see a large area of metamorphic rocks we know we are looking at the core of an ancient mountain range.

54. Changes During Metamorphism
Parent rock
(protolith)
Low temperature
Low pressure
Medium temperature Medium pressure
High temperature
High pressure
Higher temp. Higher pressure
shale
slate
phyllite schist gneiss
MELTING
quartz sandstone
quartzite
limestone
marble
basalt
amphibolite or schist
granite
gneiss

55. Metamorphic Rocks Change in metamorphic grade with depth
Increasing Directed Pressure and increasing Temps

56. Metamorphic Rocks Foliated metamorphic rock
Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied in.
Foliation: minerals have been rearranged into visible bands.

57. Metamorphic Rocks
Increasing Directed Pressure and increasing Temps

58. Metamorphic Rocks
Directed Pressure causes rocks to become folded, and minerals to reorient perpendicular to the stress: “foliation”

59. Schist

60. Gneiss

61. Slate

62. Metamorphic Rocks Non-foliated metamorphic rock
Non-foliated metamorphic rocks do not have a platy or sheet-like structure.
Metamorphic rock that does not show bands.

63. Marble

64. Quartzite