The diagrams below show the sedimentary rock layers found at two
different locations 25 km apart. Letters A, B, and C represent different
index fossils present in the layers.
surface
layer 1
layer 2
layer 3
layer 1 and layer 4
layer 4
layer 2 and layer 6
layer 3 and layer 5
layer 5
Which two layers are approximately the same age?
layer 6
surface