Unit C – Water Systems on Earth

1. Unit C – Water Systems on Earth Chapter 8 – Water Features

2. Chapter 8 – Water Features 8.1 – Geological Features at Sea and on Land

3. Geological Features at Sea and Land • Alfred Wegener came up with the theory of continental drift which led to the development of the theory of plate tectonics

4. Plate Tectonics • Earth’s crust is divided into huge sections called tectonic plates

5. Plate Tectonics • The plates collide with, slide by, slip under, and separate from each other forming a variety of features, both underwater and on land

6. Continental Shelves • Continental Shelf – the gently sloping slope of the ocean floor as it extends outward from the continents • The continental shelf is a continental plate even though it is underwater

7. Continental Slope • Continental Slope – the more steeply sloped region at the edge of the continental shelf

8. Continental Rise • Continental Rise – a region of gently increasing slope where the ocean floor meets the continental slope

9. The Ocean Floor • The ocean floor is beyond the continental slope and rise • Much of the ocean floor consists of large flat areas known as ABYSSAL PLAINS • Over time sediments from rivers and streams settle on the ocean floor filling up holes

10. Underwater Mountains • The longest mountain range in the world is underwater – The Mid-Ocean Ridge • The mid-ocean ridge is home to many volcanoes • Volcanoes that formed underwater are called SEAMOUNTS

11. Underwater Mountains • Overtime the lava builds up and forms a volcanic island – ex. Hawaiian Islands • Guyot – was once a volcanic island but has weathered and eroded enough that the ocean has covered it over again

13. Canyons • CANYONS – deep, steep-sided valley. • Most are formed by rivers that cut their way through the surrounding rock. As the rivers run into the ocean they may continue to carve away the continental shelf

14. Trenches • TRENCHES – formed when two oceanic plates collided • Trenches run parallel to the coast • Trenches may be 200 km wide and 2400 km long

15. Lakes and Rivers • See page 222 in text book

16. Watersheds • WATERSHED – an area surrounded by high-elevation land, in which all water runs to a common destination

17. The Continental Divide • The CONTINENTAL DIVIDE (or the Great Divide) – the crest of the Rocky Mountains that separates water flowing to the west from water flowing to the north and east. • See fig. 9 p.224 in txt

18. Chapter 8 – Water Features 8.2 – Glaciers: Rivers of Ice

19. Glaciers • Glacier- a mass of ice and snow built up over thousands of years • Glaciers occur in high altitudes and near Earth’s poles

20. Glaciers • The lower layers of a glacier are turned into clear ice by the weight of the snow above • This great weight also causes glaciers to ooze down mountains

21. Glacial Features • Over thousands of years, the erosion by glaciers changes the shape of mountains and creates many geological features • These features are evidence of past glaciation

22. Glaciers • As the glacier moves over uneven ground, the ice sheet breaks and produces deep cracks called crevaces

23. Glacial Features • Cirque – the small beginning of a glacier, where snow, ice and the freeze-thaw cycle create armchair-like hollows in the sides of mountains

24. Glacial Features • Arête – a landform created when two cirques on a mountain erode to each other and create a sharp ridge between them

25. Glacial Features • Horn- the sharp pyramid shape formed on a mountain when three or more arêtes carve the mountain peak

26. Glacial Features • Hanging Valley- where a small glacier meets a large glacier, and the valley floor of the large glacier is below the bottom of the small glacier

27. Glacial Features • Fiords- a long, deep valley carved by a glacier that has become flooded by sea water

28. Glacial Features • Moraines- a large ridge of gravel, sand and boulders that was pushed aside by a glacier or dragged to the end of a glacier

29. Glacial Features • Esker- a long mound of sand and gravel marking the path of meltwater streams that passed through and under a glacier

30. Glacial Features • Striations- a groove or scratch on the surface of rock; caused when boulders and gravel at the bottom of a glacier are dragged along the rock’s surface

31. Glacial Features • Erratic- a large boulder that was carried by glaciers and then left behind on the land when the glacier receded

32. Glacial Features • Iceberg- a large chunk of ice that breaks off of a glacier when the glacier reaches the ocean

33. 8.4 - Currents

34. Currents • Current- Movement of water in an ocean or lake caused by temperature differences • A current caused by temperature differences is called a convection current

35. Convection Currents • Help redistribute nutrients and oxygen in lakes that are ice-covered in the winter. • Plants get nutrients from decaying plant matter and the upper layers of the water get oxygen from the plants below

36. Ocean Currents • Convection currents exists in the worlds oceans on a global scale • See p. 232

37. Gyres • Ocean Currents form consistent, circular patterns called gyres • GYRES- a large, consistent, circular pattern of ocean currents

38. Gyres • The five major gyres of the World • North Atlantic Gyre • South Atlantic Gyre • South Indian Gyre • North Pacific Gyre • South Pacific Gyre

39. Gyres • Each gyre is made up of several currents

40. Great Pacific Garbage Patch • http://www.youtube.com/watch?v=-K-lGDRZOqc&feature=related • http://www.youtube.com/watch?v=tnUjTHB1lvM • Rd p.235 in txt book

41. 8.5 – Water, Weather & Climate

42. Water, Weather & Climate • Specific Heat Capacity – is a measure of a substance’s capacity to keep its heat • Substances with a low specific heat capacity require little heat before their temperature starts to rise • Substances with a high specific heat capacity require more heat energy to increase their temperature – these materials also take much longer to cool down because they have more heat energy to give off

43. Water, Weather & Climate • Water has a high specific heat capacity • Large bodies of water, such as oceans, warm up and cool down much more slowly than the surrounding land and can affect the weather and climate of an area

44. Water, Weather & Climate Weather Climate Climate- the average weather conditions over many years • Weather- the daily atmospheric conditions, such as temperature, precipitation, and humidity

45. Water, Weather & Climate • Water releases its heat much more slowly than land. During the night, therefore, the land cools down more than the ocean. • The air over the land also becomes cool and pushes air out to the ocean. This is known as a land breeze.

46. Water, Weather & Climate • During the day, the land warms up more than the ocean. The air above rises and a sea breeze blows in from the ocean

47. Currents and Climate • Ocean Currents have a major effect on world climates • Rd Currents & Climate p.238 - 239

48. 8.6 - Waves

49. Tsunami • Tsunami – a large wave caused by earthquakes, volcanic eruptions, or giant underwater landslides

50. Tsunami • Tsunamis are barely noticeable when they first form in the ocean <50cm high • Can travel at speeds of 800 km/h – when this energy is squeezed into shallow waters, it becomes concentrated, and the wave speeds up and increases in height