Pangaea
One of the earliest attempts to explain formations of landforms was introduced by Alfred Wegener in the early 1900's. Wegener introduced his continental drift hypothesis called Pangaea. He proposed that a super continent called Pangaea began breaking into smaller continents about 200 million years ago. These smaller continent fragments then drifted to their present positions. Certain kinds of evidence were used to prove this chain of reasoning. Among them were the "fit of South America and Africa, fossil evidence, rock types and structures, and ancient climates." (Tarbuck and Lutgens, 507). However, the continental drift hypothesis failed to provide an acceptable mechanism for the movement of continents.
Harry Hess in 1962 formulated the idea of seafloor spreading, which states that new seafloor is being generated at the mid-oceanic ridges and old, dense seafloor is being consumed at the deep ocean trenches. Hess's sea-floor spreading idea was widely accepted "with the discovery of alternating stripes of high-and-low-intensity magnetism that parallel the ridge crests." (Tarbuck and Lutgens, 507).
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