One of our great geologic forefathers, Thomas Chamberlain, the founder of Geology Journal, warned of the peril of thwarting the advancement of scientific thought if the principle of multiple working hypotheses was not embraced by researchers. Chamberlain concluded that science would become biased toward a particular scientific philosophy if we were not careful to perpetually consider other lines of reasoning that fit the observations and were physically reasonable; that is, they obeyed physical laws.
I’m afraid the geologic community has neglected Chamberlain’s warnings and that we have headed down a biased path where any paradigm contrary to traditional uniformitarianism and plate tectonics theory is considered heresy today.
However, if one were to openly and honestly evaluate some of the large scale problems associated with plate tectonics, we could perhaps begin to consider other more physically realistic mechanisms for what we observe today.
Below I will begin be addressing 10 problems (there are many more) with plate tectonics that need further investigation and discussion.
1. No adequate explanation exists for how plate tectonics began (where did the plates come from) or how subduction originated?
Nowhere in the literature does any scientist adequately address how the observed “plates” came into existence in the first place. Perhaps more perplexing is how subduction commenced. The scientific community seems to concur that plate tectonics began at some point in Earth’s history, yet no one seems to know how such a process could possibly begin. In other words, how could a 60km thick (conservative estimate) oceanic lithosphere with an average density of about 3.0-3.4 g/cm3 begin to subduct into a mantle with an average density of between 4-5.7 gm/cm3 and with greatly increasing geostatic pressures with depth (see figure below). This would be equivalent of trying to push a sledgehammer into the ground. It can’t be done. Furthermore the face of the lithosphere on the overriding plate (see figure below) would begin to flow because no “cliff” could be supported that is 60km high. Nothing remotely approaching lithospheric thickness occurs adjacent to trenches so it is unrealistic to suggest that the lithosphere has subducted beneath continental lithosphere that is at least 60km thick. No adequate mechanism has been given to explain these contradictions in physical reality.
The first and most common explanation for subduction is that as the oceanic lithosphere ages and cools, its density increases so that an instability arises and the plate sinks spontaneously in the mantle under its own weight” (Gurnis et al., 2004). However, numerical modeling has shown “that it is highly unlikely that the entire lithosphere at a fracture zone will spontaneously founder” (Hall et al., 2003). “A self-sustaining subduction zone does not form from a homogeneous plate” (Gurnis et al., 2004). Researchers found that “no combination of fault rheology or geometry produced self-sustaining subduction without applied convergence” (Hall et al., 2003). Sleep (Sleep, 1992) provided another theory that subduction initiated as dip-slip motion along strike-slip accrectionary zones. However, Sleep concurs that the oceanic plates were likely rigid, so the matter of subduction still becomes an issue of physical laws (see #3 below).
Another theory for the initiation of subduction purports that externally applied compressive stresses and moderate convergence are necessary to form a new subduction zone (Gurnis et al., 2004). The most likely mechanism would be through a transfer of stress induced by a collision, leading to ‘forced’ subduction initiation elsewhere. Yet we see no recent evidence that collisions lead to subduction. On the contrary, all recent geologic collisions have resulted in continent-continent collisions leading to large mountain ranges. The formation of the Alpine-Himalayan chain represents the collision of India and Africa with Eurasia in the closure of the Tethys Ocean. If large-scale collisional stress transfer occurred, we would expect subduction to have initiated elsewhere within the Indian and African plates. However, no new subduction zones have initiated south of either India or Africa.
Gurnis, Michael, Chad Hall, Luc Lavier. 10 July 2004. Evolving force balance during incipient subduction. Geochemistry Geophysics Geosystems, Volume 5, Number 7, pp. 1-31.
Hall, Chad E., Michael Gurnis, Maria Sdrolias, Luc L. Lavier, R. Dietmar Muller. 2003. Catastrophic initiation of subduction following forced convergence across fracture zones. Earth and Planetary Science Letters, Vol. 212, pp. 15-30.
Sleep, N.H., 1992. Archean plate tectonics: what can be learned from continental geology? Canadian Journal of Earth Science, v. 29, p. 2066-2071.
2. There is no adequate driving force for plate tectonics.
Perhaps the biggest problem with plate tectonics is the idea of whole mantle convection. No evidence exists to support mantle convection, but the physical laws to contradict such a process are overwhelming. That is to say, no physical mechanism exists for such a process to commence and this concept contradicts physical laws and even other plate tectonic principles such as theory and location of observed hot spots.
Today, radioactivity is provided as the mechanism for both convection and the existing amount of heat in the core. However, there is no evidence to support the existence of radioactivity below the upper mantle. If radioactivity represented the driving force for convection then why don’t we observe large amounts of radioactive elements in deep-seated volcanic eruptions (so called hot spots)?
Another argument against convection comes from the nature of melts within the mantle. Magma is more compressible than the rock from which it came. (Agee, 1998). Rock that melts under the extreme pressures more than 220 miles below the earth’s surface will contract and occupy a smaller volume than it did before melting! (At about 220 miles of depth, melted rock occupies nearly the same volume as the original solid rock.) At atmospheric pressure, rock expands by 7–17% when it is heated and melts. The density where the rock’s volume does not change as it melts is called the crossover density (Urakawa et al., 2006). The exact crossover depth depends on the minerals present. Because of magma’s compressibility, magma below this depth of about 220 miles is usually too dense to rise, so magma cannot circulate inside the mantle (see illustration below).
This concept of a crossover depth also supports earth’s density structure. Melts below 220 will sink toward the outer core through large fracture zones (not subducting plates) causing the outer core to increase in size over time. Melts above this depth rise to the crust in escape at volcanoes. Plate Tectonic theory seems to indicate that the density stratification occurred long ago in earth’s history but do not indicate how convection of nearly solid rock could commence. The physics of melts do not support convection. If convection doesn’t occur, neither can plate tectonics.
Introductory textbooks talk about hot spots that represent volcanoes that have magma chambers that extend deep into to mantle, some believe to the outer core. Hot spots are thought to occur at fixed locations in the mantle and as the overlying lithosphere moves (through convection) over the fixed heat source it creates a linear chain of volcanoes over geologic time. An example that is often used in the literature is the chain of Hawaiian Island seamounts. There are a number of problems with this idea. A total of 42 hot spots have been identified throughout the earth (see figure below). Many of these hot spots would have to occur within a convection cell. For example, the Atlantic basin is often used as the example for dual convection rising and spreading outward from the mid-ocean ridge and the width of the cell extending outward to a subduction zone (eg the west coast of North America). Yet numerous hot spots occur within the Atlantic basin (see red labeled dots on second figure below). The proposed mechanism for hot spots makes it impossible for large-scale convection to occur. How can a deep mantle plume (see item #9) occur within a convection cell? This idea contradicts many physical and thermodynamic laws. Consequently, convection and hot spots simply can’t coexist. A subducting plate would also obstruct mantle convection.
In addition, the shape of the mid-ocean ridges would suggest that convection would have to change directions in the middle of a cell. How is this even feasible? Furthermore, there are volcanic island chains (hot spots?) that run perpendicular to the Hawaiian Islands. The lithosphere can’t be going in opposing directions to produce such a configuration. No textbooks point out this contradiction.
A convection cell large enough to drive the Pacific plate would have to have a cell width-to-depth ratio that would be nearly 100:1, which we don’t observe in nature (eg. the atmosphere, where the convection cell has a width-to-depth ratio of about 1:1).
Agee, C.B., 1998, “Crystal-liquid density inversions in terrestrial and lunar Magmas,” Physics of the Earth and Planetary Interiors, Vol. 107, p. 63.
Urakawa, S., et al., 2006, “Anomalous Compression of Basaltic Magma,” Research Frontiers, p. 114. Also available at www.spring8.or.jp/pdf/en/res_fro/06/113-114.pdf.
3. The force balances suggest that it is physically impossible for subduction to occur.
The frictional forces required for subduction to occur are enormous and rarely do earth scientists address this problem, let alone the fact that the subducting plate is less dense than the material its supposedly plunging into. Let’s look at a simple force balance calculation for this scenario.
Consider a subducting plate (see illustration below) that has a length L, a thickness, t, a unit depth h, a density ρ2, and is inclined at an angle relative to land surface. The plate undergoes a compressive stress through the earth’s rock mass that has a constant (for simplicity) density ρ1. Solid-to-solid friction between the slab and the host rock occurs with a coefficient of μ and acts to a depth h. The lithospheric pressure at a depth of z is the mean density ρ1gz. A drag force F opposes movement at the leading edge of the plate.
In order to make subduction as likely as possible, we make the following assumptions:
• The thrusting force, σt, is perfectly aligned with the subduction angle θ.
• The thrusting force is the maximum possible, but does not exceed the crushing strength of the subducting plate.
• The plate is denser than the mantle surrounding it (This assumption is necessary or else the plate would not sink. Actually, the mantle through which the plate must push, is much denser than the plate).
For the plate to subduct, the sum of the forces acting down and to the left must exceed the sum of the forces acting up and to the right (in the illustration). That is,
Net thrust + body forces > friction on top and bottom surfaces
(σt–F) + g(ρ2–ρ1)Ltsinθ > (ρ1g(h/2)Lμ) + (ρ1g(h/2)+ρ2gtcosθ)Lμ
In dimensionless form, this simplifies to
(σ-F/t)/(ρ1gLsinθ) + (ρ2/ρ1 -1) > (L/t + (ρ2/ρ1)cotθ)μ
The coefficient of static friction for rock is about 0.6 and is not temperature dependent until temperatures exceed about 350oC. Typical values for the inequality are as follows:
σ = 2×10^8 N/m^2
g = 9.8 m/sec^2
ρ1 = 3200 kg/m^3
ρ2 = 3500 kg/m^3
L = 160 km
t = 80 km
μ = 0.6
In order to make subduction more likely, we assume here that F = 0. Substituting these values in the above inequality gives the false statement that
0.04 + 0.09 > (2.0+1.894)*0.6, or
0.11 > 2.34
Clearly the inequality cannot be satisfied. Thus, a pushing force cannot produce subduction. Recall that this includes the subduction-favorable assumption of no drag force (F=0). Even if we lower the friction coefficient to 1/19 of the current typical value we cannot get the inequality to work in the favor of subdution.
A pulling force cannot be occurring because rocks have no tensile strength. Therefore, based on this rather simple but useful exercise, we can see that subduction cannot occur.
4. There is a huge mass balance problem regarding ridges and trenches
For the earth to remain the same size over time, the amount of crust being created at ridges would have to be equal to the amount of plate being subducted along trenches. If more mass is being created than consumed, then the earth’s volume would be increasing. There is no evidence to support earths growing volume. However, based on the fact that there are 46,000 miles of ridges and only 15,000 miles of trenches, this would suggest that the earth would have to be expanding, otherwise there would be a huge mass-balance problem. Furthermore, why are trenches located primarily in the western Pacific ocean, whereas ridges are more equally developed over the entire earth?
The scientific literature contains countless papers purporting to prove subduction, but if examined closely, estimates of subduction velocities are usually inferred from midocean ridge growth rates, or are based on suggestive geophysical data without empirical measurements to prove the direction and velocity of motion. One location in which it would be easy to make strain or deformation measurements of spreading is in Iceland where the mid-ocean ridge is located above the ocean surface. However, such evidence is never presented in textbooks. The reason is likely not because such measurements haven’t been made but rather because no spreading has ever been measured, which would put the theory of plate tectonics in serious jeopardy.
5. Plate tectonics cannot adequately explain the configuration or large number of volcanoes (seamounts and guyots) in the Pacific basin.
More than 40,000 sumarine volcanoes (many of which are seamounts) are located in the Pacific basin; whereas very few seamounts are found in the Atlantic. Plate tectonics cannot answer this peculiar phenomenon. Furthermore, most of the 2,000 known guyots are concentrated in the western Pacific, between Hawaii and Japan and between 8o and 27o north latitude. Clustered guyots sometimes differ in elevation and depth by 1,000–2,000 feet, even if they are the same distance from a ridge. Furthermore, they can occur alongside a seamount of greater height. This configuration of seamounts and guyots does not fit the plate tectonic model if these features were formed along speading centers. Sediments, including dead organisms, continually fall onto ocean floors, but guyots have few sediments. Currents over guyots are too slow to sweep off sediments. This implies that guyots are geologically young.
If these volcanoes are moving with the plate, then certainly we should observe volcanoes in trenches or at least find scraped-off volcanoes in trenches, yet we find no such occurrences.
6. Plates cannot subduct in an arc.
This is one of my biggest and yet most simple arguments against subduction. Take a thick paperback book and bend it in half downward. Notice that the book bends only in a straight line. This would be also true for a thick rigid lithosphere. It is physically impossible for the lithosphere to subduct in an arcuate shape without either significant compression in a concave shaped arc or extension in a convex shaped arc. Along trenches with concave arcs, massive folds and mountain building would be evident along the hinge of the subducting lithosphere. Similarly where convex trenches occur, large extensional faults perpendicular to the trench would have to occur, yet we observe neither of these two conditions. The entire Pacific basin has trench systems that are arcuate in shape, not straight as must occur by physical laws of mass balance. Clearly, another process created these trenches. These cannot be locations of subduction based on lack of observational evidence of what we MUST see along these arcs.
7. Plate tectonics cannot explain why there are no seamounts in trenches, or why there is no evidence of scraped off seamounts in trenches.
If plate tectonics is a slow process and if seamounts form along spreading centers or hot spots and migrate as the lithosphere floats over a convecting mantle, then surely these large mountains would eventually reach a trench and either inhibit subduction (like throwing a wrench in a gear box) or the mountain would be scraped off during subduction and we’d find evidence of such a large and likely dramatic physical process. However, not only do we not find evidence for what should have occurred hundreds or thousands of times in the geologic past, we don’t even see seamounts in trench zones anywhere in the world today. Why? Plate tectonics cannot explain why but we need to ask why or how this can be.
8. The mantle plume model that PT theory uses to support spreading centers cannot work on the basis of the structure, morphology, and stratigraphy that currently exist along the ridge network
Geologists have argued for decades about mechanisms for new oceanic material being formed at mid-ocean ridges and causing spreading of the lithosphere away from the ridge crests. Most geology textbooks describe a mantle plume model as representing the source of spreading and new crustal material, the same theory that is used to explain hotspots. A model of this type is needed to support plate tectonic theory and the concept of a spreading center. There are several problems with this theory. First, the supposed source of new crustal material has never been adequately explained. This theory cannot address the current observed ridge system because it would require hundreds or thousands of individual plumes because of the many ridge offsets that occur along the ridge axis. The plume would have to occur directly beneath the ridge crest for equal spreading to occur from this midpoint. This theory is simply not feasible. Anderson (2000) states, “Deep narrow thermal plumes are unnecessary and are precluded by uplift and subsidence data. The locations and volumes of ‘midplate’ volcanism appear to be controlled by lithospheric architecture, stress and cracks.” Furthermore, as Sheth (1999) concludes “All the evidence that has been used so far to support the plume model—geochemical, petrological, thermal, topographic—is equivocal at best, if indeed not contrary. The plume idea is ad hoc, artificial, unnecessary, inadequate, and in some cases even self-defeating, and should be abandoned.” If there is continuous and constant spreading at the mid-ocean ridge system, why haven’t measurements been made in Iceland where the ridge system goes through this country? It would be a simple task to set up GPS or other land-based laser system to accurately monitor spreading rates of 4-6 centimeters per year (the rate claimed in textbooks). The more likely explanation is that these types of measurements have been done, but no spreading has been observed.
As a consequence of uplift caused by the magma plume beneath the ridge axis, slow crustal growth occurs at the ridge system causing slippage along transform faults as a result of uneven spreading occurring on a spherical earth. Geologists erroneously claim that earthquakes in fracture zones occur only between the two offset ridge axes, where the plates, according to PT theory, are moving in opposite directions past one another. This is contrary to what is observed. Earthquakes occur all along fracture zones.
Evidence indicates that the fracture zones are trough-shaped near the ridge axes where the fractures should be deepest (van Andel, et al., 1967). At the ends of the fracture zones, the profiles are V-shaped. Furthermore, the sediments inside these fractures zones are found to be undeformed (Meyerhoff and Meyerhoff, 1967)! If the opposite sides of a fracture zone are sliding past each other, sediments caught between the sliding plate segments would be highly deformed.
In at least 8 places along the mid-ocean ridges, segments of the ridge overlap for about 10 miles (McDonald and Fox, 1983). According to plate tectonic theory, plates are moving away perpendicularly from a spreading center. Therefore, the distance between overlapping segments must be increasing. However, the overlapping regions are always near each other. PT theory cannot explain this clear contradiction.
In the Pacific basin along the East-Pacific rise, a large fracture zone actually crosses over another large fracture zone (non parallel fractures). This observation cannot be explained by plate tectonic theory.
Anderson, D.L., 2000, The Thermal State of the Upper Mantle; No Role for Mantle Plumes: Geophysical Research Letters, Vol. 27, p. 3623.
Macdonald, K.C., and Fox, P.J., 1983, Overlapping spreading centers, Nature, Vol. 302, p. 55–58.
Meyerhoff, A.A., and Meyerhoff, H.A., 1967, Tests of plate tectonics: Plate Tectonics: Assessments and Reassessments; editor C.F. Hahle, 108p.
Sheth, H.C., 1999, Flood basalts and large igneous provinces from deep mantle plumes: Fact, fiction, and fallacy: Tectonophysics, Vol 311, p. 23.
Van Andel, et al., 1967, The intersection between the Mid-Atlantic ridge and the Vema fracture zone in the north Atlantic: Journal of Marine Research, Vol. 25, p. 343-351.
9. How can subduction zones and spreading centers exist at the same location?
Yet there are three locations in the Pacific basin where trenches and ridges are concomitant. These locations are at: 50.5oN latitude and 130oW longitude, 20.5oN latitude and 107oW longitude, and 46.3oS latitude and 75.7oW longitude. The same— or even closely spaced—mantle material cannot be going both up and down at the same time and at the same place.
The only known or documented evidence for magma eruptions along spreading centers is where these ridges coincide or occur adjacent to trenches. Hence, an argument cannot be made that the entire ridge system is experiencing such magma flows. In fact there is no evidence along the mid-Atlantic ridge, for example, of magma flows.
10. Crustal GPS signals on the earth do not support plate tectonics theory.
Global GPS stations reveal that a vast majority of the GPS monitoring stations indicate that the observed motion is toward the northwest Pacific basin. Perhaps more surprisingly is the fact that the motions do not conform to rigid “tectonic” plates (outlined in blue in illustration below).
Even on a globe (spherical surface), the vector directions do not produce a pattern that would conform to rigid plate motion.
Many of the references and illustrations here come from Dr. Walter Brown’s book “In the Beginning”: www.creationscience.com