Question

In addition to paleomagnetism, what other evidence was needed to determine the rate of seafloor spreading?
A.
the strength of the magnetic field
B.
the age of each strip of rock
C.
the minerals in the rocks
D.
the thickness of the rock layers

Answer 1

Other than abundant matching fossils and sedimentary rock on opposite sides of the Atlantic Ocean and the apparent puzzle piece appearance of the continents on either side of the Atlantic, there is the presence of the mid-oceanic ridges, areas where new oceanic crust is created. The magnetic orientation of the basaltic oceanic crust as it forms is the mirror image of the magnetic orientation of the basaltic oceanic crust on the other side of the ridge, indicating that the seafloor is spreading in both directions away from ridge. Additionally, the dating of rock on the ocean floor has shown that oceanic crust and overlying sediment become progressively younger as the mid-ocean ridge is approached.


And finally, accurate measurements have been made by global positioning devices which verify that seafloor spreading is occurring.