this is the figure please answer questions 1 3 and 4 Part 2. Using Magnetic Reve

Question

this is the figure

please answer questions 1 3 and 4

Part 2. Using Magnetic Reversals to Examine Sea Floor Spreading The figure on the next page shows the bathymetry expression (i.e, topography) and magnetic anomalies for the Pacific-Antarctic Ridge and the age of the magnetic reversals for the last 4.49 Ma (million years) Oceanic ridges show a symmetrical bathymetry expression. Does the magnetic field show a similar mirror image symmetry across the ridge? 1. 2. Each peak represents a normal period of polarity li.e. like today) and each trough represents a period of reversed polarity. Shade the upper half of each peak with your pencil to get a pattern of black and white stripes. Next match your stripes to those in the column to the left. Label the ages of the peaks. (Note - large broad peaks can always be correlated, whereas small peaks represent either short intervals of normal polarity or background noise. Match the large peaks up first.) How many times has the polarity changed as shown by the magnetic reversals across the Pacific-Antarctica Ridge? 3. For the last approximately 5 million years, have times of normal and reversed polarity been the same length? 4. Is there any regular pattern found in the reversals?

Explanation / Answer

1)

yes the magnetic field will show exact mirror or opposite image symmetry of the ridge. It is as if the sea-floor was a giant tape recorder, with twin tapes emerging from the mid-Atlantic ridge, recording the Earth's magnetism at the time they emerge and then traveling in opposite directions. Similar magnetic strips were also observed in all other oceans.

3) yeds the magnetic polarity lenghth always keep constant in length. every half million of years the direction of the polarity changes that the north becomes south and the south becomes north

so we can say the polarity direction gets changes every half million years of time. so we can say that the length of the polarity is always get constant.

4)

from geological measurements about the patterns of change in the magnetic field during a reversal. We might expect to see, based on models of the field run on supercomputers, a far more complicated field pattern at the Earth's surface, with perhaps more than one North and South pole at any given time. We might also see the poles 'wandering' with time from their current positions towards and across the equator. The overall strength of the field, anywhere on the Earth, may be no more than a tenth of its strength now.

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