657842078-Magnetic-Reversal.powerpointpresentation

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1. HELLO FRIENDS!!!

2. 1. Describe how Magnetic Reversal supports the Seafloor Spreading Theory; State how magnetic reversal related to seafloor spreading; 3. Appreciate the importance of magnetic reversal by relating its effect in some processes on earth. OBJECTIVES:

3. A BOUNDARY BETWEEN YOU AND ME

4. Magnetic Reversal Reversals: Magnetic Flip

5. THINK, PAIR, SHARE

6. Look for a partner and share what you have learned from the video presented. THINK, PAIR, SHARE

7. What is magnetic reversal? How scientists know about this? Why magnetic reversal can be related to seafloor spreading? GUIDE QUESTIONS:

8. Have one representative in each group to discuss their answers to the class. Student’s answer will be scored with the following rubrics: 5 points- the learners’ answer contains very relevant idea to the given concept 3 points – the learners’ answer contains nearly relevant idea to the given concept 1 point - the learners’ answer contains irrelevant idea to the given concept

9.  What is magnetic reversal? (Ans: It is when the North Pole is transformed into a South pole and the South Pole becomes the North Pole)

10.  How scientists know about this? (Ans: because of the magnetic minerals of the magma)

11.  Why magnetic reversal can be related to seafloor spreading? (Ans: because of the magnetic patterns in magnetic rocks especially those found in the ocean floor)

12. Four (4) groups . Study Figure 14 Magnetic Reversal (LM pp.65) (Ans: It represent the magnetic anomaly)  What does the stripes represent?  What are the two (2) kinds of magnetic anomaly? (Ans: The positive magnetic anomaly and the negative magnetic anomaly)

13. Magnetic anomalies.  The intensity of the magnetic field is measured at the earth's surface with a  magnetometer. Local magnetic features or anomalies are usually related to different rock types.  Rocks have different magnetic characteristics that, when added to the overall regional magnetic pattern, create anomalies. Magnetic anomalies  are areas of magnetism that are either higher or lower than the average magnetic field for the area. A  positive magnetic anomaly  is a reading that exceeds the average magnetic field strength and is usually related to more strongly magnetic rocks, such as mafic rocks or magnetite‐bearing rocks, underneath the magnetometer. A  negative magnetic anomaly  is a reading that is lower than the average magnetic field.  

14. Four (4) groups . Study Figure 14 Magnetic Reversal (LM pp.65)  What is magnetic reversal? (Ans: It happens when the North Pole is transformed into a South Pole and the South Pole becomes the North Pole)  How does it proved seafloor spreading? Ans: Because it changed the direction of flow in the outer core  What does this indicate? (Ans: It indicates that indeed, the seafloor is spreading.)

15. The Earth has a magnetic field, as can be seen by using a magnetic compass. It is mainly generated in the very hot molten core of the planet and has probably existed throughout most of the Earth's lifetime.

16. The magnetic field is largely that of a dipole, by which we mean that it has one North pole and one South pole. At these places, a compass needle will point straight down, or up, respectively.

17. By magnetic reversal, or 'flip', we mean the process by which the North pole is transformed into a South pole and the South pole becomes a North pole.

18. How often do reversals occur?

19. Magnetic reversals happened many times in the past . The occurrence of magnetic reversals can be explained through the magnetic patterns in magnetic rocks, especially those found on the ocean floor . When lava solidifies, iron-bearing minerals crystallize . As these crystallize, the minerals behave like tiny compasses and align with the Earth’s magnetic field. So when a magnetic reversal occurs, there is also a change in the polarity of the rocks. This allowed scientists to visualize the magnetic stripes in the ocean floor, and to construct a magneticpolarity time scale

20. Over the last 10 million years, there has been an average of 4 to 5 reversals per million years . New rocks are added to the ocean floor at the ridge with approximately equal amounts on both sides of the oceanic ridge. The stripes on both sides are of equal size and polarity which seemed to be mirror images across the ocean ridge. What does this indicate? It indicates that indeed, the seafloor is spreading!!!

21. Magnetic polarity map based on the magnetic polarity map the average rate of plate movent is 2.5 cm per year but NOT ALL plates move at the same rate.

22. Does magnetic reversal brings any danger to life?

23. Almost certainly not. The Earth's magnetic field is contained within a region of space, known as the magnetosphere , by the action of the solar wind. The magnetosphere deflects many, but not all, of the high-energy particles that flow from the Sun in the solar wind and from other sources in the galaxy.

24. Human beings and their ancestors have been on the Earth for a number of million years, during which there have been many reversals, and there is no obvious correlation between human development and reversals. Similarly, reversal patterns do not match patterns in species extinction during geological history.

25. Some animals, such as pigeons and whales, may use the Earth's magnetic field for direction finding. Assuming that a reversal takes a number of thousand years, that is, over many generations of each species, each animal may well adapt to the changing magnetic environment, or develop different methods of navigation.

26. LET’S EVALUATE

27. Create a song by group about the topic for today and the time is maximum 3-4 minutes to present. Your score is based on the rubrics.