Is the theory of Continental Drift true?
The question before us is indeed interesting. That a seperation of the continents did occur is certainly true, however I am afraid I must take issue with the standard model and expound my views towards a preference for ‘expanding earth’ theories of continental drift over more traditional concepts of ‘plate techtonics’. It goes without saying that elements of this established notion are also, invariably of high value and remain true. I will attempt to be subtle yet thorough in my analysis of the similarities and differences between the two models, and why I believe what I do, without detracting from the overal assignment.
As I mentioned, I do not have any issue with the idea of ‘continental drift’, there can be no doubt from simple observation (and more detailed data which we shall hereafter explore) that, at the very least, parts of South America and Africa were once much closer in proximity than they are today, indeed perhaps they were even directly connected. Moreover we cannot ignore the distribution of plant and other proto-life around the globe. Even a child can plainly detect the jig-saw fit between the coasts on the east and west Atlantic Ocean, but the biological and fossil records reveal even more upon examination and consideration.
Regardless of our preference of opinion regarding the mechanics or means of drift theory, we can deduce that the ends are certain, that the continents were at one time joined even though they are now seperated by miles upon miles of oceanic expanse. There are a number of bodies of research which support this position. Data related to mesosaur, plant and glacial distribution have yeilded some of the strongest support for the idea of drift. From the diagram below we can see that creatures in the distant pass had easy access to the various present land masses in what is now the southern hemisphere.
Throughout this analysis we will gather data from several fields which support the theory of continental drift. We have already addressed one, biology. The distribution of mesosaurs and some types of proto-mammals, marsupials, and others all point towards a geologic history which included easy access between the continental regions for animal life.
In paleobotanical studies we see that across the entire southern region of the planet the fern Glossopteris is found on all coninental regions. In the north aswell, as illustrated in the diagram below, the trees all share a similar genetic ancestry indicating one contiguous landmass at some point.
This diagram illustrates similarities in the diversity of some plant species across vast regions. We should note that the areas of present-day Eastern South America and Central-South Africa contain high levels of diversity, implying similarities beyond the geologic jigsaw. From this map we can see correlation between the Phillipene and the Central American/Caribbian regions in their density which may imply a ‘total’ Pangea with Pacific-Bio-Jigsaw fit.
In our mesosaur maps we saw easily that the southern regions had been connected in pre-history, but this map includes illustrations on the similarity in plant distribution across the northern hemisphere which is excluded from the previous diagram. Even though we notice similar increases in density in the south and central regions, here we also see less diversity is similar through North America and the northern Eurasian areas. Examples of global plant fossilization which point us towards acceptance of a unified planetary suffaceinclude various grasses, seeds and planet-wide examples of Lycopodiophyta among other things. It is worth noting here that the amount of diversity is similar over North America and North Eurasia but so is the contents of that diversity. The evergreen and oaks that grow in Canada and the corrisponding areas across the oceans are one in the same. Their lack of divesity has preserved them, and this correlation, for our examination. There are always going to be specific localized varieties in areas of great diversity, but even the presence of plant life in all quarters of landmass not innundated with heat or frost suggests either simultaneous distribution or easy access at one time across the now disperate regions.
Much established data is existant regarding glaciation of the southern portions of pangea. I believe this is because of two main reasons. One, there seems to be a great deal of hesitation about cosing up the pacific rift in these models. By leaving the northern and western most portions unexamined, theories of a constant earth size and traditional plate techtonics can be more easily maintained. Two, this may also be in part because the northern polar cap is without landmass, but again I wonder how much of this is because of a reluctance to close up the pacific much as we do with the atlantic in simulations. There seems to be equal or greater growth indicated in the pacific area from the analysis of the ocean spread, yet in models showing the progression of pangea this area seems to have been ever covered in water, 75% of the Earths surface. I believe this would result in destabilization of orbit, but admittedly this is only speculation. However regarding the paleoglaciation of the southern region; the polar ice cap which we are able to identify from the carboniferous period, covers the southern end of pangea. Glacial deposits, specifically ‘till’, of the same age and variety are found on many now separate continents as a result of the migration and termination of this glaciation.
There is indeed a great deal of evidence to support the theory of plate techtonics. Not least of which is the plates themselves. Using seismographs and other methods, geologists have been able to actually map the shapes and locations of these plates with, what is presumed to be, a great deal of accuracy. I have faith in this data also. I do believe that beneath the surface, the continents and parts of the ocean shelf may ride on a hardened series of plates as described. What I am not so sure about is subduction; it seems to me areas of subduction are mountainous indicating the plates are pushing up not down into the Earth (their age correlates roughly to that of the ocean floor also, the highest ranges being only some estimated 40- 70,000,000 years old. Even though we do know that the ocean floors are spreading, plate techtonics theory does little to address the differences in age between the seafloor and the continental crust (and the size difference). The difference in age is quite tremendous. When this age data is examined it leaves us with a map and details of how the Earth seems to have grown. While subduction and creation of the ocean floor are possbile and allow for the maintenance of size, I believe the evidence of the age of the underwater shelfs indicates that at one point the entire planet was mostly solid on the surface, much smaller and with perhaps small traces of water in the form of lakes or chemical pools dotting the surface. However, later on, I believe an ice meteor or something similar crashed to the earth and interfered with the natural cycles inside. I think this caused a variety of heating and cooling to occur which resulted in destabilization of the size to some degree, part became hotter and the Earth expanded perhaps because of the liquid nature of part of the interior. I also deduce that the composition of the impact site, considering the meteor and the planet at that time, caused for the massive distribution of water around the globe and unleashed a great change in the planets overall composition and dimension on the outside, the cooling from the formed water and ice deposits may have cooled and stabelized the planet surface. Once more, much of this is speculation, but if we do not measure continued growth then there must have been a reason for the changes at that time. The fact that we still measure new production and subduction may be residual from the fractures in the interior structure which, though healed, seem as molten scars of an old wound. I believe that this impact likely occurred in the Mexican peninsula and this shattered completely the landmass of the caribbian and phillipines and caused a tremendous and lasting push through the pacific. Obviously these theories are incomplete. From my present humble position I cannot verify these claims, they are simply my deductions and observations from this study of continental drift.
Mostly from these studies I have developed an understanding of how limited our knowledge base is on these topics, how new the field and how intersting and important these studies can be. The implications are tremendous. We really have not explored into the earth very much. It even seems to me that it has been easier for us to get into space than it has been for us to get into the Earth to a very significant degree. Perhaps current plate theory is the ‘end all be all’ of this geologic research. It has certainly helped to cement the debate around continental drift into a very one sided affair. We are no longer concerned with if the continents did or are drifting, rather we are interested in why or how they did or are.
The purpose of this assignment was to address wether the theory of continental drift is accurate. In my opinion drift is accurate, but plate techtonics is only the tip of the proverbial iceburg.
I would encourage you to observe the following digital maps and videos of ‘growing earth’ theory.
Continental Seperation Animation - http://www.youtube.com/watch?v=7kL7qDeI05U
Bibliography for Study and Data related to plate techtonics and continental drift.
The Eruption of Mt. St. Helens (1975-1995) - http://www.youtube.com/watch?v=dRfXn6WzetI
Plate Techtonics (1976 Production) - http://www.youtube.com/watch?v=rzWKR--ovbI&feature=PlayList&p=12491D2AE0BC3C02&index=0&playnext=1
Bio-Diversity Map Study - http://www.nees.uni-bonn.de/infodocs/MutkeBarthlott_2005_GlobalDiversity_BiolSkrift.pdf
Continental Drift, Wikipedia - http://en.wikipedia.org/wiki/Continental_drift
- PLANET EARTH – Johnathan Weiner (1986) [Fully Illustrated with data and maps]