NIST Year 9 Dynamic Earth

Monica Bugielski

Alfred Wegener's fully developed theory of continental drift attempted to point out evidences that the continents were once joined into a single continent he called Pangea. Wegener's theory hypothesized that the continents were able to push through the rock of the seafloor to their present positions. As evidence, he noted, as had others before him, of the geographic correlation in coastline perimeters of South America and Africa. This was the feature that led Wegener to investigate for other evidences. His investigations revealed that mountain ranges in South America and Africa, and strata and composition of coal fields in Europe and North America matched or lined up. Additionally, matching reptilian fossils were found on either side of the ocean, indicating that the continents were once joined together. Although he was unable to find a mechanism for his proposed continental drift theory, he also observed that the more shallow an ocean, the younger its geologic age. It wasn't until the 1950's and 1960's, with the discovery of the Mid-Atlantic Ridge, and other sea floor mapping discoveries that Wegener's hypothesis started to become more accepted. The newer science of plate tectonics owes much to Wegener's scientific groundwork.

Alfred Wegener first thought of this idea by noticing that the different large landmasses of the Earth almost fit together like a jigsaw.

The Continental shelf of the Americas fit closely to Africa and Europe, and Antarctica, Australia, India and Madagascar fit next to the tip of Southern Africa.

He analyzed either side of the Atlantic Ocean for rock type, geological structures and fossils. He noticed that there was a significant similarity between matching sides of the continents, especially in fossil plants.

Alfred Wegener proposed the theory of continental drift at the beginning of the 20th century. His idea was that the Earth's continents were once joined together, but gradually moved apart over millions of years. It offered an explanation of the existence of similar fossils and rocks on continents that are far apart from each other. But it took a long time for the idea to become accepted by other scientists.Before Weg

Wegener suggested that mountains were formed when the edge of a drifting continent collided with another, causing it to crumple and fold. For example, the Himalayas were formed when India came into contact with Asia.

se the Earth was cooling down, and in doing so contracted. This was believed to form wrinkles, or mountains, in the Earth's crust. If the idea was correct, however, mountains would be spread evenly over the Earth's surface. We know this is not the case.