Our Dynamic Earth

1. Our Dynamic Earth

2. Earth as a System • The Earth is an integrated system that consists of rock, air, water, and living things that all interact with each other. • Scientists divided this system into four parts: • The Geosphere (rock) • The Atmosphere (air) • The Hydrosphere (water) • The Biosphere (living things)

3. Earth’s Interior • Scientists use seismic waves to learn about Earth’s interior. • Seismic waves are the same waves that travel through Earth’s interior during and earthquake. • A seismic wave is altered by the nature of the material through which it travels.

4. Layers of the Earth • Scientists divide the Earth into three layers: • The crust • The mantle • The core • These layers are made up of progressively denser material toward the center of the Earth.

5. Processes and Forces that Affect the Lithosphere • Rock Cycle • Weathering • Erosion • Soil Formation • Plate Tectonics • Earthquakes • Volcanoes • Humans

6. Rockin’ the Rock Cycle

7. Rock Cycle • 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 through the rock cycle.

8. What is a Rock? Naturally-occurring mixtures of minerals, mineraloids, glass or organic matter. Rocks are divided into 3 groups based on how they were formed: IGNEOUS SEDIMENTARY METAMORPHIC

9. Igneous Rock Igneous rock is made when magma cools and crystallizes. (Igneous means “from fire or heat”)

10. Examples of Igneous Rock Granite: Large/Course Grains Basalt: Small/Fine Grains Obsidian: Glassy/Very Fine Grains

11. What happens to the Igneous Rock? 1. It can be weathered and eroded and turned into small pieces, called sediment, which can then be turned into a sedimentary rock. 2. It can be put under high heat or pressure and form a metamorphic rock. Could melt and become magma again

12. Sedimentary Rock 1. Rock is weathered and forms sediments • Sediments: smaller pieces of rock • Examples: Gravel, Sand, Mud, Soil

13. Sedimentary Rock 2. Erosion The process by which weathered rock and soil particles are moved from place to place by wind, water, gravity, glaciers, etc. 3. Deposition The process by which weathered sediments are laid down in a new location creating new landforms through “bedding”.

14. 3. Deposition – Types of Bedding Bedding – oldest sediments on the bottom, youngest sediments on top 2. Graded Bedding – biggest sediments on bottom, smallest on top (happens in water) 3. Cross Bedding – sediments are laid at an angle (ex: sand dunes)

15. Sedimentary Rock CoalSandstoneShale 4. Lithification - Sediments must be buried, compacted, cemented together to make a sedimentary rock. • Examples of Sedimentary Rock:

16. What happens to Sedimentary Rock? 1. Could weather and erode to become sediments which cement and compact to form sedimentary rock 2. It can be put under high heat or pressure and form a metamorphic rock. Could melt to form magma which cools and hardens to form igneous rocks.

17. Metamorphic Rock Limestone (Sedimentary)  Marble Shale (Sedimentary)  Slate Granite (Igneous)  Gneiss Formed from existing rocks. Are created by intense heat or intense pressure. Can be foliated = looks like it has layers (made from pressure) Can be non-foliated = does not look like it has layers (made from heat)

18. What happens to Metamorphic Rock? Could weather and erode to become sediments that cement and compact to form sedimentary rocks 2. Could melt to form magma which cools and hardens to form igneous rocks

19. How are rocks redistributed? The core, mantle, & crust are one giant rock recycling machine changing the lithosphere.

20. Weathering

21. Weathering Weathering is the breaking down of rocks and other materials on the earth’s surface

22. Physical Weathering Breaks rock into smaller pieces without changing the overall composition. Examples- Biological Activity (tree roots and animals burrowing), Frost Wedging (water freezing inside cracks of rocks causing them to expand and break), Gravity

23. Chemical Weathering Chemical reactions that change the overall composition of the rock. Examples- Water (most important agent), Acid Rain on gravestones (dissolves minerals), Oxidation

24. In which shape will weathering occur faster?

25. Factors that determine the rate of weathering: • Composition Granite more resistant than marble. • Physical conditions of rock • Cracks, holes, crevices – easier weathering • Solid, unbroken – more weather resistant • Topography: the position of the rock • Air pollution • Exposure time • Surface area exposed • Climate • Cold Climates– mechanical weathering breaks down rocks rapidly • Warm, wet climates – chemical weathering breaks down rocks rapidly Mechanical and chemical weathering work together

26. Erosion

27. 5 Agents of Erosion Gravity Glaciers Wind Water Ocean Waves

28. Soil Formation

29. Soil formation starts with… Weathering Erosion Deposition

30. Followed by… Some living organisms such as bacteria, fungi and insects. They die, decay and add nutrients to the soil.

31. So Basically… Soil is a layer at the surface of the earth composed of a mixture of weathered rock, organic matter, mineral fragments, water, and air which is capable of supporting the growth of plants impacting the lithosphere.

32. Plate Tectonics

33. What observations can you make about the shape of the continents?

34. What’s interesting? Just 200 million years ago, this is what the world looked like:

35. Plate Tectonics • Tectonic plates- blocks of lithosphere that consist of the crust and the rigid, outermost part of the mantle and glide across the underlying asthenosphere. • The continents are located on tectonic plates and move around with them. • The major tectonic plates include the Pacific, North America, South America, Africa, Eurasian, and Antarctic plates

36. Plate Boundaries • Much of the geological activity at the surface of the Earth takes place at the boundaries between tectonic plates. • Tectonic plates may separate, collide, or slip past one another.

37. Plate Boundaries Divergent Boundary:

38. Plate Boundaries Divergent Boundary: • Plates are moving away from each other • Midocean ridges are created and new ocean floor plates are created

39. Rift Valleys Leif the Lucky Bridge Bridge between continents in Reykjanes peninsula, southwest Iceland across the Alfagja rift valley, the boundary of the Eurasian and North American continental tectonic plates.

40. Plate Boundaries Convergent Boundary: • plates are moving toward each other and are colliding (3 types)

41. Create subduction zones, trenches Create near coast volcanoes Island arcs are created Mountain ranges are created (example: Himalayan Mountains) Convergent Boundaries

42. Himalayan Mountains

43. Plate Boundaries Transform Fault Boundary • Plates are neither moving toward nor away from each other, they are moving past one another.

44. Transform Fault Boundary • The plates may move in opposite directions or in the same directions but at different rates and frequent earthquakes are created (example: San Andreas Fault)

45. San Andreas Fault

46. No Plates are destroyed as fast as they are created (2 ways) Plates may be subducted and melted or may push be pushed upward to form mountains So is the Earth getting bigger?

47. Tensional Force: stretching or pulling Creates a normal fault What types of forces are created?

48. Compressional Force: force pushing something together Creates a reverse fault What types of forces are created?

49. Shear or Transversal Force: a system of forces that operates against a body from different sides Creates a strike-slip fault What types of forces are created?

50. Earthquakes