B40b. SEAFLOOR SPREADING. Atlantic Getting Bigger. SEAFLOOR SPREADING. Idea that the ocean bottom is getting larger. Atlantic Ocean Proposed by Harry Hess Evidence in rocks on ocean floor. mid-ocean ridge found running down center of Atlantic Ocean series of mountains on either side.
oldest rocks on continents = 4.6 billion years old
THEREFORE: new rocks are forming
(B3, Figure 9)