Using the map of the seafloor magnetic stripe pattern at left, the distance scal
ID: 285982 • Letter: U
Question
Using the map of the seafloor magnetic stripe pattern at left, the distance scale bar, and the combined magnetic reversal time scale shown at right, what is the average rate at which the oceanic crust at point A has moved away from the ridge axis since it formed? (Answer in cm/year)
290 cm/yr Map view of the magnetic reversal pattern on the seafloor Magnetic reversal time scale reverse normal reversed 1.5 Ma 3 Ma 3.5 Ma Mid-ocean ridge axis normal normal reversed 4 Ma 5.5 Ma normal reversed Distance Scale (100 km)Explanation / Answer
3.3 centimeter on scale = 100 km
Distance between point A and B = 6.8 centimeter on figure
Distance between point A and B in kilometer = (6.8/3.3) x 100
Distance between point A and B in kilometer = 206.060606
= 206.060606 x 1000 meters = 206060.606 meters
206060.606 meters = 20606060.6 cm
Time for movement = 3.5 million years = 3.5 x 106 years
Therefore, the rate at which points A and B have been moving apart from each other = 20606060.6 cm/3.5 x 106 years
Therefore, the rate at which points A and B have been moving apart from each other = 5.88 cm/year
Which is closest to 5.7 cm/yr, hence "c" is correct.
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