Ken McIntyre SCE /17/08

History of Continental Drift The theory states that the continents were once joined together in a super continent called Pangaea and slowly drifted apart and are still moving today Pangaea

History of Continental Drift  Alfred Wegener has always been known as the father of continental drift theory, but he and the theory needed a lot of help. The idea of continental drift was so far ahead of its time it would be a paradigm shift that not one person could comprehend by themselves. Alfred Wegener Scientific paradigm is way of scientific thought that might pertain to any specific scientific concept Scientific paradigm

History of Continental Drift  Charles Lyell Charles Lyell First to proposed the idea of continental drift and plate tectonics Stated his theories of uniformitarianism in his book titled Principles of Geology.Principles of Geology. ○ Uniformitarianism is belief that the same forces that had moved the continents in the past are still at work today. Uniformitarianism

History of Continental Drift  Antonio Snider-Pellegrini Antonio Snider-Pellegrini Published a book La Creation et ces mysteres devoiles ○ Stated what the earth looked like due biblical events. ○ Was the first time the continents that surround the Atlantic Ocean where brought together.

History of Continental Drift  Osmond Fisher Osmond Fisher stated another theory in a paper published in Nature.Nature Fisher claimed that when the moon broke away from earth, the continents on the other side of the planet cracked and split apart.

History of Continental Drift  Alfred Wegener Alfred Wegener Argued that the continents were once together a single land mass called Pangaea.Pangaea Collected evidence to support theory ○ Noticed that the east coast of South America line up with the west coast of Africa like pieces of a puzzle. ○ Read paleontological papers that reported similarities of species of reptiles found in the same strata in Africa and Brazil. ○ 1915 published his theory of Continental Drift in a book entitled The Origins of Continents and Oceans.The Origins of Continents and Oceans

History of Continental Drift  Alfred Wegener cont. Made revisions of his book The Origins of Continents and Oceans. Gathered more evidence ○ Mapped mountain ranges that line up between the two continents ○ Mapped fault lines that line up between the two continents ○ Mapped and noted specific mineral deposits that line up between the two continents

History of Continental Drift  Arthur Holmes Arthur Holmes in the 1920’s had perfected the radioactive decay of rocks, which was a technique used to accurately age the Earth. ○ Technique measured the amount of uranium decay in rocks before it turns into lead produced a more detail account of what is causing the continents to drift. ○ describing how convection currents were responsible for the break up of Pangaea. Published his findings of the age of the Earth at 4.5 billion years old in a book titled Principles of Physical Geology. ○ Holmes findings are still used today when referring to the age of our planet.

History of Continental Drift  Harry Hess Harry Hess American geologist in 1960 came up with a model Sea-floor Spreading which explains how molten material from convection currents get pushed through the oceanic crust.Sea-floor Spreading Sea Floor spreading is when the oceanic crust spreads apart causing the sea floor to spread. Was able to age the rock, with the youngest rock near the ridges and the older rocks further away. ○ By aging the rocks Hess was able to measure the rate of the sea floor spreading process of the Atlantic Ocean at about 2cm/year.

History of Continental Drift  Dan McKenzie Dan McKenzie Studied data collected about the Earth’s magnetic field. Magnetic patterns of the Atlantic Ocean floor were mapped. The patterns/stripes ran north and south in line with the Earth’s magnetic field at the time when the crust was being created.

History of Continental Drift  John Tuzo Wilson John Tuzo Wilson Canadian geophysicist ○ mapped transform boundaries along the mid-ocean ridge in the Atlantic ○ Suggested that the oceanic crust is doing more than growing but also sliding past each other. ○ Coining and using the phrase “Plate” as a reference to the part of the Earth’s stiff crust. Transform Boundary

History of Continental Drift  Edward Bullard Edward Bullard 1963 was able to make an objective model based on mathematical rule to reconstruct what Pangaea would have looked like. The model proved to be easier to follow and understand because the individual continents fit together like a jigsaw puzzle.

History of Continental Drift  Dan McKenzie and Robert Parker First to publish the term plate tectonics in the journal Nature in 1967.Nature Plate tectonics was to sum up and describe the geological activity taking place to move the continents. The term is still used today.

Conclusion of the History of Continental Drift  To explain and understand the theories of both continental drift and plate tectonics was definitely a “group effort”.  It all started with Lyell and his theory of uniformitarianism in the Principles of Geology  Spawned into the theories of continental drift and plate tectonics.  So many scientists had contributed to either support or fill in the gaps that were left behind to explain how the continents have moved and still are, but none had contributed to the cause more than Alfred Wegener. Perhaps that is why he will always be remembered as the father of the continental drift theory.