Key Seafloor spreading short spring 2020

The map below shows a portion of the North Atlantic Ocean, with the Mid- Atlantic Ridge as the dark line. Dashed lines parallel to the ridge connect points with the same age. The lines are labeled with age in millions of years (my). In this exercise we consider two different rates: the rate at which new seafloor is formed and the rate at which the North American continent is moving away from the African continent. The rate at which the continents are moving apart is twice the average sea-floor formation rate. The rate at which the continents are moving apart is called the full spreading rate. The average seafloor-formation rate is called the half spreading rate. Seafloor-formation rates are calculated by dividing the distance of each point (A to E) from the Mid-Atlantic ridge by the age of the respective points. Use the scale in the figure to determine approximate distance from the ridge. The only equation you will need in this exercise is: speed = distance/time, which you see every time you drive a car. 1. Complete the table below for the locations indicated by letters. Location Approximate distance from ridge (km) Age of seafloor (my) Seafloor formation rate (km my -1 ) Seafloor formation rate (cm year -1 ) A 300 35 8.57 0.857 B 800 84 9.52 0.952 C 1400 118 11.86 1.186 D 2000 156 12.82 1.282 E 1800 156 11.54 1.154 2. What is the average movement rate in cm year -1 ? Key Seafloor spreading