The South Atlantic Ocean formed by seafloor spreading at the Mid-Atlantic Ridge.

Question

The South Atlantic Ocean formed by seafloor spreading at the Mid-Atlantic Ridge. Geologists can get a rough estimate of the spreading rate (i.e., the relative motion of South America with respect to Africa) by measuring the distance between the two continents in a direction parallel to the fracture zones and determining the time over which the spreading occurred. Measure the distance between South America and Africa along the fracture zone (indicated by the arrow) on the map in Exercise 2.2 (see p.29) km The oldest rocks in the South Atlantic Ocean, immediately adjacent to the African and South American continental shelves, are 120,000,000 years old. Calculate the average rate of seafloor spreading for the South Atlantic Ocean over its entire existence. Express your answer in km/million years = km/yr = cm/yr = mm/yr. Assuming someone born today lives to the age of 100, how much wider will the Atlantic Ocean become during his or her lifetime? cm

Explanation / Answer

Answer :a

As map is not shown, therefore measure the distance between south America and Africa on the map as given to refer page 29, and convert it into km.

Answer :b

After measuring the distance in part A(above), calculate the speed of seafloor spreading by the following formula;

Speed= Distance / time

where, time= 12*107 years

And conversion. 1 km= 1000 m= 1000,00 cm= 1000,00,0 mm

Answer: c

In this case, we have to calculate the distance by considering the speed as same in part b, and time = 100 years.

Now , put the values in following equation

Distance= Speed / time

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