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Grade 8 Science

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Ocean waters may rise Flood rivers If they disappear, rivers may dry up Drainage Basins Watershed The area of land that drains into a body of water such as a river, ... – PowerPoint PPT presentation

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Title: Grade 8 Science


1
Grade 8 Science
  • Unit 1
  • Water Systems on Earth
  • Chapter 1

2
Effects of Water?
Churchill River
3
Large Ocean Wave
4
How do you use water?
5
Water Distribution
6
  • Only 3 of the Earths water is fresh water (no
    salt).
  • 2/3 of this water is frozen in ice sheets.
  • Therefore only 1 of the fresh water on Earth is
    available.

7
Review of Terms...
  • Lithosphere the solid rocky ground of the
    Earths crust.

8
  • Atmosphere the environment surrounding the Earth.

9
  • Hydrosphere All water on Earth. Including that
    in the lithosphere and atmosphere.

10
Why do we not run out of water?
11
The Water Cycle...
12
  • The constant cycling of water through the
    processes of evaporation and condensation
  • Water is constantly changing form
  • (gas liquid)
  • Driven by the suns energy

13
Scientists who study water...
  1. Hydrologist A person who studies Earths water
    systems and helps to find solutions to problems
    of water quality and quantity.

14
  • 2. Oceanographer A person who studies all
    aspects of the ocean. They are concerned with
    the biology, geology, physics, and mathematics of
    the ocean.

15
Ocean Water vs. Fresh Water
  • Three ways in which fresh water differs from
    ocean water are
  • Salinity
  • Density
  • Freezing point

16
1. Salinity
  • The amount of salt dissolved in a specific amount
    of water.

salt comes from dissolved solids in the ground
and volcanoes.
17
  • Fresh Water
  • tiny amounts of salt.
  • Salt Water
  • Average is 35 ppt.
  • Varies depending on location.
  • at the equator and poles

18
2. Density
  • The amount of mass of a substance in a certain
    unit volume.
  • How tightly packed together the material is in a
    substance.

19
  • Ocean water is more dense than fresh water due to
    the salt content.

The Dead Sea
20
3. Freezing Point
  • The temperature at which a liquid freezes.
  • Fresh water... 0oC
  • Salt water... -1.9oC

21
Core Lab Activities
  • Activity 1-3A
  • Salinitys Effect on Water Density
  • Activity 1-3B
  • Temperature Water Density

22
Sources of Fresh Water
  1. Lakes, ponds and wetlands
  2. Streams and rivers
  3. Ground water
  4. Glaciers
  5. Drainage basins

23
Ground water...
  • Precipitation that falls on land and sinks out of
    sight.
  • Sinks through pores in rocks until it reaches
    bedrock where it pools.
  • Drilling to these pools make wells.

24
Ground Water
25
  • Runoff does not sink into the ground or
    evaporate. It flows across the Earths surface.
  • Affected by ground material, amount of rain,
    length of time it rains, slope of the land,
    vegetation, and the amount of development.

26
Glaciers...
  • A moving mass of snow and ice.
  • Found in areas where it is so cold the snow
    remains all year.

27
Glaciers in mountains and on the continent of
Antarctica
28
  • Glaciers slow down the passage of water through
    the water cycle by storing vast quantities of
    water. They release the water during the hot
    summer months.
  • They give us information about the Earths past
    climates.

29
Water trapped in glacial ice
30
The Ice Age
  • The most recent began
  • 120 000 years ago ending
  • 11 000 years ago.
  • Glaciers covered 20 of land on Earth.

31
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32
Glaciers and Global Warming
  • In the last 100 years the average surface temp.
    Has increased by 0.5oC.
  • The worlds glaciers are melting at a quicker
    paces than ever before.

33
Melting Greenland Glacier
34
Receding Athabasca Glacier in Alberta It has
receded 1.5 km since 1843.
35
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36
What does this mean?
  • Ocean waters may rise
  • Flood rivers
  • If they disappear, rivers may dry up

37
Drainage Basins
  • Watershed
  • The area of land that drains into a body of water
    such as a river, pond, lake or ocean.
  • There may be many small within a larger basin.

38
  • A divide separates one basin from another.
  • Ex. The Continental Divide

39
Canadian Drainage Basins
40
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41
6 Major Drainage Basins in NL
  1. Labrador Sea
  2. Gulf of St. Lawrence
  3. West Coast Gulf of St. Lawrence
  4. South Coast Gulf of St. Lawrence
  5. Atlantic Ocean Avalon Peninsula
  6. Atlantic Ocean North-east Coast

42
Using pencil leads, indicate the 6 major drainage
basins of NL
43
One Component Affects Another...
  • Ex. Salinity affects the types of organisms that
    can survive in an area.
  • Ex. Temperature affects the amount of dissolved
    oxygen in water. The lower the temp. the more
    oxygen.

44
  • Ex. The convergence of the Labrador current and
    the Gulf Stream influences productivity of the
    Grand Banks, the movement of icebergs, and
    migration of capelin and whales.

45
Debate Topics...
Problems/ issues related to the oceans include
  1. Seal hunt
  2. Cod moratorium
  3. Regional food fishery
  4. Oil and gas exploration
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