A comprehensive rebuttal to the Expanding Earth Theory: Part 1
Although this may seem quite silly to a lot of you, there is this increasing dialogue about a theory that counters the theory of plate tectonics. This theory is called the Expanding Earth Theory (EET) and postulates that the Earth has not been the same size throughout time but started out with a radius of around 1,700 kilometers in radius and grew into the radius it is now, approximately 6,371 kilometers. This blog will fill the oddly apparently void of a point by point rebuttal of the EET by means of structural geology, geophysics, and sedimentology.
This will be in a series of parts as it is very time consuming doing this and it takes days of preparation and research to produce only a few pages.
There are two main videos from some of the more prominent EET advocates, James Maxlow and Neil Adams. Their videos can be found on YouTube, and as these two videos are a congolmeration of the main points of the EET, I will be doing a step by step rebuttal of the James Maxlow video and then writing about the unique points of the Neil Adams video. The James Maxlow video can be found here: https://www.youtube.com/watch?v=ePyU7cyMT_k There are a lot of points of contention in these videos and I could go on for days about it, so in this blog I will be highlighting the main points of rebuttal that can be proven by physics and geology.
First we must understand the basics of the EET. It is a theory that states that the Earth had a much smaller radius than current day and that the Earth has been expanding through time on an exponential increase. This is detailed by the spreading rates and ages in the mid-ocean ridges, the apparent exact fit of all continental edges if the radius of the Earth was smaller, and the apparent inconsistencies in mantle dynamics and the sedimentary record.
The first 10 minutes of the Maxlow video is a basic introduction of the EET including the basic premise and the history of people that recognized the margins of the continents were matching from margin to margin. This introduction shows that this is not a new idea that has crossed the minds of people and is in fact something that looks plausible and logical due to the visual configuration of the plates. At around 7:15, he says that his reconstructions go back 100% of Earth’s history and that Plate Tectonics ‘struggles’ to get to 20% and is ‘not convincing’. Although true that modern plate reconstructions only can be made accurately for around 750 mya, this is not due to a lack of evidence for the mechanism of plate tectonics but merely because the surface geology of the continents, erosion, collisions and basin formations obscure a lot of history that far back.
I will now list the claims set forth by the EET and my rebuttal.
1: Coastlines of the continents must remain constant in order for the EET to function.
This line of reasoning is shown in the first 10 minutes of the James Maxlow video (or alternatively you can skip to the last 5 minutes of the video where he has his models running). This is also something that is repeated several times in the Neil Adams video, namely that if you take the existing coastlines of the world, take away the oceans and decrease the radius of the Earth, then everything will fit together.
If we look at some recent articles and books such as Fromard et al., 2004, and Boggs, 2006 (figure 1) we see that the coastlines of continents are highly variable and can be altered on the order of years and even weeks such as the case of Hurricane Katrina in the southern United States (Sallenger et al., 2007).
Another example of how the margin lines of continents can be highly variable throughout time is the occurrence of large coastal sedimentary deltas. Large river systems such as the Mississippi and the Nile transport an incredible amount of material downstream, with the Mississippi transporting 230 million tons of sediments per year (Jansen and Painter, 1974, Mead, 1982; Meade and Parker, 1984; Ludwig and Probst, 1998). This massive amount of sedimentary transport results in the increase in shoreline area and in the case of Louisiana, an entire area for agriculture and residence (figure 2)
Once we realize that the coastlines of the continents are not only easily altered by sediments from rivers but from tectonic activities such as the compression of the Himalayas, we can confidently say that the margins of continents cannot stay static for the 4.6 billion year history of the Earth.
2: The rate of expansion in the present-day is 22mm increase of radius per year “ John Maxlow”
For this problem, we need to make a comparison. If the radius of the Earth is increasing by 22mm per year, then this needs to be proportional to an increase in the surface area of the Earth. Let’s calculate that now:
where 6,371,000meters is the current radius (approximately) and 6,371,000.022 is the increase of 22mm.
Lets now take a look at the three major mid-ocean ridges and their spreading rates:
Mid Atlantic Ridge: 10,000 km in length, median spreading rate of 3 cm/year.
Pacific Ridge: 5000 km in length, median spreading of 15 cm/year
South East Indian Ridge: 6700 kilometers in length, spreading rate of 15 mm/year.
These are just the major spreading ridges and by no means represent the sum total. We can assume that the area amount of the total amount of area ‘created’ by the spreading ridges each year must be equal to the surface area increase we calculated before for the radial increase of 22mm.year.
To calculate the ‘increase’ of surface area from these spreading ridges, it is a simple length*width calculation. If we calculate this, we end up with:
Mid Atlantic Ridge:
South East Indian Ridge:
The addition of only these three areas is . This means that just based on simple arithmetic and geometries, the figure of 22mm/year of radial increase is physically not possible.
3: Subduction does not exist.
This is the main idea and parading ‘fact’ of the EET. There is no subduction of the oceanic crust under the continental crust on active margins (although they don’t distinguish between active and passive margins).
Firstly, subduction zones are not just a concept that is present only on paper. To understand how we can see these subducting plates, we need to understand what seismic tomography is. A tomographic image is merely a map of P-wave (or compression wave) velocities. Think of it this way, if you and a friend are on opposite sides of a long table and you punch the edge straight on, they are going to feel the movement very very quickly. If you do the same but with a block of jello, if they feel anything transmitting to the other end it is going to be a very small amount. This is because P-wave velocity is a function of density. The more dense something is, the faster P-waves will transmit through that material, excluding things like the outer core which are plasticine and dense so they don’t transmit the compressional waves very well (figure 3). This means that using seismic wave velocity contrasts will give us a picture of the density contrasts (Zhao et al., 1997; Fischer et al., 2000; Roth et al., 2000)
Geophysicists like Robert van der Hilst at MIT have imaged the subducting oceanic plate using seismic tomography (figure 4) across Central and South America showing that not only can geophysicists image the subducting plate, but they are able to determine the angle in which they subduct and anisotropies in the subducted plate segment.
Another major component of understanding the relationship between the surface geology of the Earth and the presence of subduction is the geochemical make-up of the magmas on active margins. An active margin is where subduction is taking place. This subduction creates compression (mountain building) and volcanoes (which I will get to in a little bit). The most obvious place to see this phenomena is on the Pacific Ring of Fire (figure 5).
This is a very important distinction. In the EET, there is no reason for these volcanoes to exist in the places they do and it takes absolutely no mention of the geochemical differences in melts produced in these volcanoes. The reason that there are so many volcanoes near a subducting plate is because of the interaction of the chemistry of the subducting oceanic plate and the mantle in which it is being subducted into. This is the reason there aren’t volcanoes everywhere on the planet because there isn’t this unique geochemical interplay (figure 6).
In the next installment I will cover the structural geology aspects of the EET, namely what happens structurally if you have a sphere that is increasing in diameter that has a solid outer crust and what features we should expect to see in such a system along with how we know the Earth isn’t a piece of the Sun that was shed off (another claim by the EET).
References and links
Fischer, K.M., E.M. Parmentier, A.R. Stine, and E.R. Wolf, Modeling anisotropy and plate-driven flow in subduction zone back-arcs, J. Geophys. Res., 105, 16181, 2000.
Fromard F, C Vega, C Proisy, Half a century of dynamic coastal change affecting mangrove shorelines of French Guiana. A case study based on remote sensing data analyses and field surveys, Marine Geology, Volume 208, Issues 2–4, 15 August 2004, Pages 265-280, ISSN 0025-3227, 10.1016/j.margeo.2004.04.018.(http://www.sciencedirect.com/science/article/pii/S0025322704001112)
Jeff Lillycrop and C. Wayne Wright and Asbury Sallenger, Coastal-Change Impacts during Hurricane Katrina: An Overview, Coastal Sediments ’07 chapter 68 pages 888-896
Jansen, J. M. L., and Painter, R. G. 1974. Predicting sediment yield from climate and topography. J. Hydrol. 21:371–380.
Ludwig, W., and Probst, J.-L. 1998. River sediment discharge to the oceans: present-day controls and global budgets. Am. J. Sci. 298:265–295.
Meade, R. H. 1982. Sources, sinks, and storage of river sediments in the Atlantic drainage of the United States. J. Geol. 90:235–252
Meade, R. H., and Parker, R. S. 1984. Sediment in rivers of the United States. U.S. Geol. Surv. Water Pap. 2275: 49–60
Robert van der Hilst 2007 http://www.geotimes.org/july07/article.html?id=feature_deeper.html
Roth, E.G., D.A. Wiens, and D. Zhao, An empirical relationship between seismic attenuation and velocity anomalies in the upper mantle, Geophys. Res. Lett., 27, 610-604, 2000.
Zhao, D., Y. Xu, D.A. Wiens, L. Dorman, J. Hildebrand, and S. Webb, Depth extent of the Lau back-arc spreading center and its relationship to the subduction process, Science, 278, 254-257, 1997.