Conclusion

All of these pieces of evidence provide sufficient proof that once the continents were joined together as a super continent 'Pangea'.

Bibliography

(2010). Student Resource Centre - Geololink. Houghton Mifflin Company. http://college.cengage.com/geology/resources/geologylink/glossary/c.html [Accessed 20th of September]

Wilson, J. (1996). Continental Drift. Colliers Encyclopedia, Vol 7. http://www.platetectonics.com/article.asp?a=18 [Accessed 21st of September]

(2010). Continental Drift. http://cosscience1.pbworks.com/Lesson+10-1+Continental+Drift [Accessed 23rd of September]

Combrink, L. (1999). An Introduction to Plate Tectonics. http://www.hartrao.ac.za/geodesy/tectonics.html [Accessed October 7th, 2010]

WGBH Educational Foundation. (2007) Continental Divide- The Break up of Pangea. http://www.teachersdomain.org/asset/lsps07_int_biogeography/ [Accessed October 5th 2010]

Edwards, J. 2005. Plate tectonics and Continental Drift. London: Evans Brothers Limited

Heffernan, D. Mahon, R. McDougall, J. Gillies, K. (2002) Spotlight Earth and Environmental Science- Preliminary. Australia: Science Press

Murck, B. Skinner, B. (1999) Geology Today- Understanding our planet. USA: John Wiley and Sons, Inc.

Direct Measurement

With the development of technology every day, the slow movement of the earth's plates can be measured directly. With the use of computers, laser measurement and satellite remote sensing the distance between two points on either side of a plate boundary can be calculated, and the rate and direction of movement of the plate can be measured.

Even though each plate will have a general direction of movement, the rate at which different parts of the plate moves can vary causing tearing or folding of the plates. These forces can create fault lines in the middle of the plates. The plates move in different directions, and at different rates meaning sometimes they collide or rub up against each other. These movements can cause earthquakes and tsunamis.

Age of ocean rocks and sediments

Radioisotope dating has helped geologists to prove that as a new crust is formed at an oceanic ridge and pulled apart sideways, rocks get progressively older the further they are from the ridge. When ages of sea floor rocks are mapped out we see the oceanic crust is that is the newest at the ridges and the oldest furthest from the ridges. This was propsed by Harry Hess in the 1960's, when he proposed tha ridges are located above zones of pressure in the mantle, resulting in the creation of new seafloor.

Sediments in the seafloor such as organic debris helps to prove this as well as there are no sediments located at the ridge and the sediment layers get thicker as you move away from the ridges and radioisotope dating helps to prove this.

This piece of evidence provides substantial proof for the continental drift theory, as it shows that new rocks are being formed continuously at the oceanic ridges, proving that the ridges were once joined and are still moving and separating today.

Palaeoclimates (ancient climates)

Being a meteorologist, Wegener was interested in the climate that earth experienced during Paleozoic times. He found evidence for dramatic global climate differences. Wegener found that glacier sheets aged between 220 and 300 million years old covered large areas of the Southern Hemisphere. Layers of glacial deposits were found in southern Africa, South America, Australia and India. Below these deposits are scratched layers of bedrock from expanding ice.

Certain types of minerals and rocks can only be created under specific conditions. One example of this is coal is formed from organic material deposited in warm, swampy areas. Antarctica has coal deposits dated to the same age as the glacial deposits, so that rules out the question could the earth have been cold enough to be completely covered in ice?

As Antractica has coal deposits and other parts of the Southern Hemisphere were covered in glaciers, the only explination for the differing in the climate of today is that the world was once joined as the super continent, Pangea.

If South Africa was centered over the South Pole, the conditions would be appropriate to form large glaciers over what is today's Southern Hemisphere and would place the northern landmasses near the tropics, resulting in coal deposits.

Fossil Distribution

Fossils help to provide further evidence that the continents were once joined together as a super continent. Geologists have found fossils of different plants and animals, on different continents that a separated by oceans. This fossilised evidence suggests that these animals evolved together and were then separated when the continents split apart.

Most of the animals that were alive in this time period have been extinct for thousands of years, so fossils are the only evidence available to provide further proof for the theory of continental drift. The distribution of these fossils shows a similar, unbroken pattern of that which the matching geological formations forms.

When Wagner suggested his theory, many were skeptical, instead scientists suggested that seeds of plants were carried by the wind and other animals migrated continents via land bridges, during an ice age. An ice age would lower the sea level allowing animals to cross Bering Strait between Asia and North America. However, if land bridges did exist, their remnants should still lie below sea level, but no signs of land bridges have ever been found in the Atlantic Ocean. Also the seeds of the Glossopteris, one of the fossils used as proof in this piece of evidence, had seeds that were too large and heavy to be carried by the wind even small distances, let alone across vast oceans.

Glacial Deposits

During an ice age, ice and glaciers spread outward over large regions from the north and south poles. When moving around, glaciers leave deep scratches on what would have been smooth rock and deposit sediments that can be identified and dated.

Paleozoic Glaciation (ancient glaciation), which took place approx. 300 million years ago, left marks on rocks that are now on several continents that are all far away from the poles like present day arid Africa. the various locations that glaciologists have found the same rock deposits, dating to the same ages, make no logical sense unless the continents together as Wegener proposed. When this is done, locations and latitudes of the Paleozoic Glaciation fall into place.