Structure of the earth

1. Structure of the earth

2. Earth’s Layers The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.

3. The Crust • Outermost layer: Named Lithosphere • Lithosphere = crust + upper mantle • The crust is only about 8 kilometers thick under the oceans (oceanic crust) and about 32 kilometers thick under the continents (continental crust).

4. The Mantle The Mantle is the largest layer of the Earth. The middle mantle is composed of very hot dense rock that flows like asphalt under a heavy weight. The movement of the middle mantle (asthenosphere) is the reason that the crustal plates of the Earth move. Is responsible for the movement of the Earths plates

5. The Core • Below the mantle and to the center of the Earth. • Two Layers of the Core: The Outer and Inner core • Contains large quantities of Iron.

6. The Outer Core The core of the Earth is like a ball of very hot metals. The outer core is so hot that the metals in it are all in the liquid state. The outer core is composed of the melted metals of nickel and iron.

7. The Inner Core The inner core of the Earth has temperatures and pressures so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place like a solid.

8. Introduction to Rocks

9. What makes up a mineral? • Different minerals are made up of different elements. • The elements include: • Silicon • Oxygen • Iron • Sodium • Chlorine • Calcium • Carbon • Hydrogen • Aluminium -Si-O-Fe- -Na-Cl-Ca- -C-H-Al-

10. Diamond Minerals Beryl (Emerald) • Some minerals form beautiful crystals and others can be prized because of their many uses: • Diamonds, Ruby, Sapphire, Emerald, gold and silver, are a few of 3000 minerals that occur naturally in rocks. • Others include: quartz, Zircon, topaz, talc. Silver Ruby Gold

11. Most rocks are a combination of two or more minerals. Mineral is a naturally occurring solid composed of several different elements. Each mineral has its own unique characteristics. A mineral is the same all the way through. What are rocks?

12. No Not only are they different colours, but there are also different types. The three main types are igneous, sedimentary, and metamorphic rocks. Are all rocks the same? Igneous: Granite Metamorphic: Gneiss Sedimentary: Sandstone

13. Cycle of Rocks • There are 3 different basic types of rocks that can be found to make up parts of the Earth’s crust: IGNEOUS ROCKS 75% of the Earths crust SEDIMENTARY ROCKS 5-10% of the Earth’s crust METAMORPHIC ROCKS 15 % of the rocks exposed on the Earth’s surface

14. Rocks are created, transformed, and destroyed in a process called The Rock Cycle Where do rocks come from?

15. First of all there is no real beginning or end to the rock cycle! However, for this lesson we will begin with igneous rocks. Igneous rocks often forms when lava erupts from volcanoes then cools. There are 2 Types of Igneous rocks - Intrusive & extrusive The rock cycle: Part 1

16. Extrusive Rocks EXTRUSIVE– Formed when magma ERUPTS from volcanoes or escapes through cracks to form lava. Lava cools quickly – and forms into rocks. Fine-grained, e.g. Pumice and basalt. Rhyolite Obsidian Andesite Basalt

17. Intrusive Rocks • INTRUSIVE - Formed when magma slowly solidifies inside earth. Takes thousands of years to harden. Not seen until surface rocks have been eroded away. Coarse-grained. Diorite Gabbro Granite

18. Igneous rock is a volcanic rock that forms when magma cools and hardens. Intrusive igneous rock solidifies underground. Extrusive igneous rock solidifies above ground. Igneous Rock Definition

19. Secondly, the rock cycle is not a perfect circle, it does not occur in a specific sequence. Igneous rocks can be re-melted, eroded, or pressed. Rocks that are formed from eroded or weathered rock are Sedimentary Rocks. The rock cycle: Part 2

20. Sedimentary Rocks • Erosion --> rocks and minerals break down into small pieces called sediments. • Carried by ‘the elements’ & deposited in river beds or sea beds. • Accumulate (build-up) in layers --> pressed together by weight of new sediments. Compressed sediments are ‘cemented’ & harden to form new rock. Sea Land Weight and pressure of sediment particles

21. Sedimentary Rocks • Have you ever noticed layers or bands in rocks? These are the layers of sediment. • Examples: Sandstone, limestone, chalk and shale • Fossils are often found in sedimentary rocks. Why do you think this might be?

22. Sedimentary Rock Definition Sedimentary rock is a rock formed near Earth’s surface from pieces of other rocks, plant or animal remains, or by the build-up of chemical solids. Images source: www.geology.com

23. Finally, rocks can be transformed over time to make new rocks. Heat and pressure can create new rocks. These rocks are called Metamorphic rocks. The rock cycle: Part 3

24. Metamorphic Rocks • Igneous and sedimentary rocks can be changed into a different kind of rock by extreme heat or pressure – the changed rock is called metamorphic rock. • Original rock may be forced into new arrangements, sometimes new minerals form. • Metamorphic rocks can also change again. Examples: Shale --> Slate Limestone --> Marble Granite --> Granite gneiss Sandstone --> Quartzite

25. DEFINITION Metamorphic rock is a rock formed by the transformation of existing rock, as a result of extreme heat and/ or pressure. Images source: www.geology.com

26. Review: The Rock Cycle • Rock is constantly being changed by; heat, pressure, melting, crystallization, compaction, cementation and weathering. • Move rock material through the states of; melts, igneous rock, sediments, sedimentary rock and metamorphic rock. • This natural and ongoing cycle is known as the rock cycle.

27. HOW OLD IS THAT ROCK?

28. Plate tectonics AND THE THEORY OF CONTINENTAL DRIFT

29. The Lithospheric Plates The crust of the Earth is broken into many pieces called plates. The plates "float" on the soft, semi-rigid asthenosphere. Each plate has a name.

31. Distribution of Fossils • Plant and animal fossils found on the coastlines of different continents

32. “Puzzle Pieces” • Continents look like they could be part of a giant jigsaw puzzle

33. Continental Drift Theory • Proposed by Alfred Wegener in 1912 • 250 million years ago, all of the continents were combined into one super-continent called “Pangaea” • The continents gradually drifted apart to where they are today!

34. Continental Drift

35. Continental drift flipbook • Each map contains an approximate year • Start with the most recent and colour each continent in a different colour • Work your way back to the oldest map, colouring each landmass in the same colours as the first map • Cut out the flipbook along the dotted lines • Put the pages in order according to date (oldest on top) • Staple the pages on the let side • Answer these questions in your book: • When does Pangea appear to break apart? • When can you identify Laurasia and Gondwana? • When can you first recognise North America? Africa? Australia? India?

37. Plate boundaries • On the map provided, colour each plate a different colour (DON’T USE RED) • Name each plate • Draw/colour in the location of the Ring of Fire in RED • Glue this map into your exercise book • Answer the following questions in your book underneath the map • Does Australia sit at the edge of a continental plate? • Does the location of Australia mean it will be unaffected by plate tectonic movements? Explainyour answer.

38. Plate movement

39. Divergent Boundaries • Boundary between two plates that are moving apart or rifting   • RIFTING causesSEAFLOOR SPREADING

40. Features of Divergent Boundaries • Mid-ocean ridges • rift valleys • fissure volcanoes

44. Convergent Boundaries • Boundaries between two plates that are colliding   • There are 3 types…

45. Type 1 • Ocean plate colliding with a less dense continental plate • Subduction Zone: where the less dense plate slides under the more dense plate • VOLCANOES occur at subduction zones

47. Andes Mountains, South America

48. Type 2 • Ocean plate colliding with another ocean plate • The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH

50. Aleutian Islands, Alaska