Final answer:
To determine which seafloor spreading ridge is faster, we analyze the magnetic stripes representing ages of rocks on the ocean floor. The East Pacific Rise is known for faster spreading due to wider spaces between age bands compared to the Mid-Atlantic Ridge. Age bands at a greater distance from the ridge center in the Pacific than in the Atlantic indicate a faster spreading rate in the Pacific.
Step-by-step explanation:
To compare the seafloor ages between the mid-Atlantic Ocean and the Pacific Ocean, off the coast of South America, and determine which spreading ridge is spreading faster, we look at the data provided on seafloor ages. In the mid-Atlantic Ocean, the Mid-Atlantic Ridge is a site where new seafloor is being created by seafloor spreading. This seafloor spreading is evidenced by symmetrical stripes of rock that form on either side of the ridge, with the youngest rocks being closest to the ridge and progressively older rocks being found farther away. We can determine the rate of spreading by measuring the distance of these bands from the ridge and considering the age of the rocks.
When comparing this to the Pacific Ocean, near the East Pacific Rise off the coast of South America, we often see faster spreading rates. The East Pacific Rise is known for its rapid creation of new seafloor due to faster tectonic plate movement. By analyzing the ages of the seafloor using magnetic stripes that correspond to Earth's historic magnetic field reversals, we can compare the distance from the ridge center to the same age bands in the Atlantic and the Pacific. This comparison reveals that the bands in the Pacific are further apart, indicating a faster rate of seafloor spreading there. Additionally, comparing the width of these bands and their corresponding ages offers insight into the variability of spreading over geological time frames.
The ages of the seafloor help in determining the spreading rates because the older bands indicate how long the seafloor has been spreading. By measuring the distance from the ridge to the oldest bands and knowing their age, we can calculate an average spreading rate for each ridge. For instance, if the same age band is found further from the ridge in the Pacific Ocean than in the Atlantic Ocean, it suggests that the Pacific has been spreading faster over the same amount of time.