Oceanic crust is denser than continental crust. so when the two meet, oceanic crust subducts under continental crust. this fact best supports which claim? a. the hardest rocks on earth are in the oceanic crust. b.the hardest rocks on earth are in the continental crust. c.the oldest rocks on earth are in the oceanic crust. d.the oldest rocks on earth are in the continental crust.3.a geologic cross section of the himalayan mountain range is shown below.