1. 3 types of rocks

2. 3 types of rocks There are 3 types of rocks found on Earth:
Igneous
Sedimentary
Metamorphic
Knowing the differences between these 3 types of rocks allows us to learn about Earth’s past.

3. Igneous Rocks - Formation
Igneous Rocks are formed by melting, cooling, and crystallization of other rocks.
Igneous rocks form as a result of volcanic activity, hot spots, and melting that occurs in the mantle.

4. Igneous rocks
Igneous rocks are common along plate boundaries or mantle hot spots

5. Igneous Rocks - Classification
Igneous rocks are classified using their texture in the following ways:
Glassy
Aphanitic (no visible crystals)
Phaneritic (visible crystals)
Porphyritic (Some visible and some not visible crystals)

6. Igneous Rocks - Texture
Crystal size is used to classify igneous rocks.
Crystals form as the rock cools, and the crystal size can tell us a lot about its cooling history:
The larger the crystals, the slower it cooled.

7. Igneous Rocks - Texture
Glassy igneous rocks have no crystal structure, and probably formed by very rapid cooling (such as on the surface of a lava, or when a lava enters the water.)

8. Igneous Rocks - Texture
Aphanitic rocks have no visible crystals, and probably formed by fast cooling above ground.

9. Igneous Rocks - Texture
Phaneritic rocks have visible crystals, and probably formed by slow cooling below ground.

10. Igneous Rocks - Texture
Porphyritic rocks have both visible and nonvisible crystals, and probably formed by two different cooling events.

11. Igneous Rocks - Classification
Dark igneous rocks are formed from basaltic or mafic magma. (Mafic because it contains a lot of magnesium and iron).
The magma that forms these rocks is usually very hot (around 1000°C) and viscous (about the same viscosity as ketchup.)

12. Igneous Rocks - Classification
Light colored igneous rocks are formed from silicic (high silica content) or felsic magmas.
The magmas that form these rocks is usually more cool, (lower than 850°C), and more viscous (about the viscosity of peanut butter.)

13. Igneous rocks - Formations
Structures and formations seen in igneous rocks include:
Hexagonal columnar joints
Pahoehoe lava flows
Dikes, sills, and batholiths (plutons)
Pillow basalts
Volcanoes

14. Igneous Rocks - Examples
The most common types of igneous rocks include:
Rhyolite
Andesite
Basalt
Granite
Diorite
Gabbro

15. Igneous rocks charted

16. Igneous rocks - Story
What do you know about the history of the Earth in the place where this rock was found?

17. Sedimentary Rocks - Formation
Sedimentary rocks are formed by weathering, erosion, deposition, compaction, and cementation of other rocks.
Sedimentary rocks form in areas where water, wind, or gravity deposit sediments.

18. Sedimentary rocks - formation
Sedimentary rocks are likely to form in areas such as:
Deltas
Beaches
Rivers
Glaciers
Sand dunes
Shallow seas
Deep oceans

19. Sedimentary rocks - Classification
Sedimentary rocks are classified into two groups:
Clastic rocks
Chemically formed rocks

20. Sedimentary rocks – Classification
Sedimentary rocks are Clastic if they are made of pieces of other rocks that have been weathered and eroded.
Clastic rocks are grouped based on the size of grain that they are made from.

21. Sedimentary rocks - Classification
Very small particles make up mudrock.
Medium sized particles make up sandstone.
Large particles make up conglomerates.

22. Sedimentary rocks - Classification
Sedimentary rocks that form from chemical processes are called biochemical rocks (formed from living things) or Chemical precipitates (formed from lakes or shallow seas.)

23. Sedimentary rocks - formations
Structures and formations seen in sedimentary rocks include:
Stratification
Cross bedding
Graded bedding
Ripple marks
Mud cracks
Fossils

24. Sedimentary rocks - Examples
Some of the most common types of sedimentary rocks include:
Conglomerate
Sandstone
Shale
Limestone
Gypsum
Oolites
Chert (including black flint and red jasper)

25. Sedimentary rocks - Story
What do you know about the history of the Earth in the place where this rock was found?

26. Metamorphic rocks - Formation
Metamorphic rocks are formed by heat and pressure changing one type of rock into another type of rock.
Metamorphic rocks form near lava intrusions, at plate subduction zones, and in deep mountain roots.

27. Metamorphic rocks - Formation
Lava intrusions can provide heat that causes metamorphic rocks to form. These small areas of metamorphic rock form from contact metamorphosis.

28. Metamorphic rocks - Formation
Rocks that metamorphose because of increasing heat and pressure found at plate subduction zones and in deep mountain roots form large areas of metamorphic rock through regional metamorphosis.

29. Metamorphic rocks - Classification
Metamorphic rocks are classified into 2 major groups:
Foliated
Nonfoliated

30. Metamorphic rocks - Classification
Foliated rocks form when differential pressure causes minerals to form in layers.
These rocks will have stripes or planes that they will break easily along.
These “stripes” don’t usually line up with the original bedding planes in sedimentary rocks.

31. Metamorphic rocks
Nonfoliated metamorphic rocks formed in areas where the pressure from all sides was equal, so there is no “linear” quality to the rocks.

32. Metamorphic rocks - Formations
Structures and formations seen in metamorphic rocks include:
Folding
Plastic deformation
Stretching
Alternating dark and light layers (gneissic foliation)

33. Metamorphic rocks - Examples
Some common types of metamorphic rock include:
Slate
Schist
Gneiss
Amphibolite
Marble
Quartzite
Metaconglomerate

34. Metamorphic rocks - Charted

35. Metamorphic rocks - story
What do you know about the history of the Earth in the place where this rock was found?