For more than a century, scientists have recognized that opposing margins of continents fit together in certain ways and display geological and paleobiological evidence of having been joined in the past [1], as illustrated at left by the 1858 drawing of Antonio Snider-Pellegrini.

Early in the twentieth century, Alfred Wegener, pictured at right, proposed that the continents at one time had been united, but subsequently had separated and drifted through the ocean floor to their present positions [2]. Wegener’s theory of continental drift, vigorously opposed for half a century, was revived in the 1960s, and modified to become plate tectonics theory. When plate tectonics theory was originally proposed, there was much discussion and debate, but eventually, plate tectonics became the stuff of textbooks, its potential problems and a competitive theory rarely, if ever, mentioned.

In science, advances are made, not by cataloging a theory's successes, but by revealing its short-comings. Too often people think that mantle convection "must" exist because plate tectonics seems "correct", rather questioning whether there might be a problem with mantle convection. J. Marvin Herndon, pictured at left, did in fact question mantle convection and found a serious problem [6]. Indeed, the critical assumption of mantle convection is truly the Achilles heel of plate tectonics.

When a fluid is heated from beneath, it expands becoming lighter, less dense, than the fluid above it. This top-heavy arrangement is unstable, so fluid motions result as the fluid attempts to restore stability. The top-heavy arrangement occurs because the temperature at the bottom is hotter than at the top. This is convection. Not only is the Earth’s mantle not a fluid, but the weight of over-burden rock causes compression within the mantle, which increases with depth. Matter at the bottom of the mantle is about 62% more dense than at the top, as shown in the figure at right. Heating bottom-rock causes a miniscule increase in volume, hence miniscule decrease in density, much, much less than 1%. This is far, far too little to make the "parcel" of bottom-mantle light enough to float to the top, not enough to make the mantle top-heavy; the result is no mantle-convection at all. Moreover, the tacit assumption that the solid mantle behaves as an ideal gas with no viscous loss, i.e., adiabatic, is incorrect as evidenced by earthquakes at depths as great as 660 km.

Often Earth-mantle convection is (wrongly) "justified" by calculating a high Rayleigh Number. But, as discovered by Herndon, Lord Rayleigh's derivation was based upon constant density and, thus, is not applicable to the Earth's mantle [6].

So, unequivocally, plate tectonics theory is not correct. Why? Because the crucial underlying part is physically impossible, which means that plate tectonics theory is wrong. That might not be surprising as plate tectonics is an incomplete theory, a theory without an energy source to power geodynamic activity.

Decompression of the Earth may be seen as a direct consequence of the subsequent removal of hydrogen and other volatile constituents from the compressed kernel, presumably during the thermonuclear ignition of the Sun, as illustrated at left. After being stripped of such a great overburden, the Earth would rebound, tending toward a new hydrostatic equilibrium. Gravitational energy of compression, stored during the Jupiter-like proto-planetary stage, may be seen as the primary energy source for driving geotectonic activity, augmented to a much lesser extent by nuclear fission and radioactive decay energy [24, 25].

After being stripped of its massive Jupiter-like shell of gases, by the T-Tauri super plumes, the initial whole-Earth decompression is expected to result in a global system of major primary decompression cracks appearing in the rigid crust which persist as the basalt feeders for the global, mid-oceanic ridge system, as illustrated at right. But here the similarity with Earth expansion theory ends.

As viewed from the surface in idealized representation, Whole-Earth Decompression Dynamics is characterized primarily by the following two distinct, but related, processes: (i) the formation of secondary decompression cracks (often near continental margins), and (ii) the in-filling of those cracks with basalt (produced by volume decompression in the mantle), which is extruded mainly at mid-oceanic ridges, solidifies and traverses the ocean floor by gravitational creep to regions of lower gravitational potential energy, ultimately plunging downward into and in-filling distant decompression cracks.

As the Earth subsequently decompresses, the area of the Earth’s surface increases by the formation of secondary decompression cracks, often located near the continental margins, presently identified as oceanic trenches. These secondary decompression cracks are subsequently in-filled with basalt, extruded from the mid-oceanic ridges, which traverses the ocean floor by gravitational creep, ultimately plunging into and in-filling secondary decompression cracks, as illustrated schematically at left. If animation stops, please refresh page. For Windows, press F5.

Note that, in Whole-Earth Decompression Dynamics, no mantle convection is required to explain, in a logical, causally related way, the features of ocean floor that previously have been attributed to plate tectonics and to seafloor spreading.

Whole-Earth Decompression Dynamics extends plate tectonic concepts as it is responsible for Earth’s well-documented features. Fold-mountain formation does not exclusively require plate collisions. Partially in-filled secondary decompression cracks uniquely explain oceanic troughs, inexplicable by plate tectonics. And, compression heating at the base of the rigid crust is a direct consequence of mantle decompression. Plate tectonic meanings and terminology are to a great extent preserved in my new paradigm. For example, transform plate boundaries are identical; divergent plate boundaries are similar, but with a different driving mechanism; convergent plate boundaries likewise are similar, but down-plunging plates neither create oceanic trenches, which are secondary decompression cracks, nor are they recycled through the mantle by conveyer-like mantle convection, and; Wadati-Benioff earthquake zones are quite similar, with the possible exception of why mantle melting occurs that is responsible for sometimes associated volcanic eruptions. Many of the plethora of observations, taken to support plate tectonics, support Whole-Earth Decompression Dynamics as well.

The timescale for whole-Earth decompression is not yet known with certainty. One might think that whole-Earth decompression should have commenced promptly upon removal of protoplanetary hydrogen and other volatile constituents, but even the time of the initial primary crack formation is not known. The timescale for decompression may be related to the pre-degasification protoplanetary thermal state, to the dynamics of degasification, especially the cooling that might have been involved, to mantle properties, to the cooling that results from decompression, and to the time required to replace heat lost by decompression cooling. Further, the energy required for initiating a crack is generally considerably greater than the energy required for crack propagation.

The timescale for the Earth’s full rebounding from protoplanetary compression may be long, even extending into the present; witness, for example, the relatively minor rebounding of northern land masses, following post-Pleistocene deglaciation, being measured in thousands of years [27]. A much, much longer time may be expected for rebounding from compression due to protoplanetary-scale loading by approximately 300 Earth-masses of volatile constituents.

The Earth appears to be approaching the terminus of its decompression. If the Earth is presently decompressing, length of day measurements should show progressive lengthening.  Such measurements, made with increasing precision over the last several decades, show virtually no current lengthening [28], implying no current secondary decompression crack formation. The formation of secondary decompression cracks might be episodic, though, like the release of stress by major earthquakes, or secondary crack formation may have ended forever. But major secondary decompression cracks are still conspicuously evident, for example, circum-pacific trenches. And, the complementary Whole-Earth Decompression Dynamics process of basalt extrusion and crack in-filling continues at present.

Secondary crack formation and the in-filling of those cracks are complementary elements of the same Whole-Earth Decompression Dynamics process. Even in the absence of current secondary decompression crack formation, an estimate may be obtained of recent-period whole-Earth decompression by considering the amount of in-filling basalt presently being produced. The value obtained is consistent with length of day measurements [12]. Much higher basalt extrusion rates undoubtedly have occurred in the past, as the present estimated annual percent increase in radius, if constant over the lifetime of the Earth, would have only resulted in a 2 percent increase in radius.

Previously in geophysics, only three heat transport processes have been considered: conduction, radiation, and convection or, more generally, buoyancy-driven mass transport. As a consequence of Whole-Earth Decompression Dynamics, J. Marvin Herndon added a fourth, called mantle decompression thermal-tsunami [29].

As illustrated at right, heat generated within the core from actinide decay and/or fission [19, 20] or from actinide decay within the mantle may enhance mantle decompression by replacing the lost heat of protoplanetary compression. The resulting decompression, beginning at the bottom of the mantle, will tend to propagate throughout the mantle, like a tsunami, until it reaches the impediment posed by the base of the crust. There, crustal rigidity opposes continued decompression, pressure builds and compresses matter at the mantle-crust-interface, resulting in compression heating. Ultimately, pressure is released at the surface through volcanism and through secondary decompression crack formation and/or enlargement.

Mantle decompression thermal-tsunami poses a mechanism for emplacing heat at the base of the crust, which may explain the geothermal gradient, temperature becoming greater with depth within the crust. Moreover, it may prove to be a significant energy source for earthquakes and volcanism, as these geodynamic processes appear concentrated along secondary decompression cracks. The nature of heat transport in the Earth is described in detail by Herndon [30].

In J. Marvin Herndon’s view, virtually all major geological activity is the consequence of a single process: Earth-crust fragmentation – splitting the Earth’s crust to form new surface area to accommodate decompression-increased planetary volume. Crustal fragmentation, called rifting, provides all of the crucial components for petroleum-deposit formation: basin, reservoir, source, and seal. Rifting causes the formation of deep basins, as presently occurring in the Afar triangle of Northeastern Africa. Augmented by heat channeled upwards from deep within the Earth, uplift from sub-surface swelling can sequester sea-flooded lands to form halite evaporate deposits, lead to dome formation, and can make elevated land susceptible to erosion processes, thus providing sedimentary material for reservoir rock in-filling of basins. Moreover, crustal fragmentation potentially exposes deep basins to sources of abiotic mantle methane and, although still controversial, methane-derived hydrocarbons [31].

YouTube Video: No Mantle Convection!!! (click here) Plate tectonics theory is incomplete, providing no energy source for geodynamics and depends critically on the assumption of mantle convection. This video shows the reason that mantle convection is physically impossible.

YouTube Video: 21st Century Earth Dynamics Part 1 (click here) and 21st Century Earth Dynamics Part 2 (click here) This is a two-part video about a complete, new geodynamic theory, recently published in the scientific literature, called Whole-Earth Decompression Dynamics, that unifies and supersedes plate tectonics and Earth expansion theories.

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