Posted by: Barry Bickmore | May 18, 2017

No, There Is No Magma Ocean

This is part of a series of articles responding to the claims made in Dean Sessions’ Universal Model.  Click the link to see the introduction to the series.

Dean Sessions, author of the Universal Model, apparently thinks scientists are pretty stupid.  The constant refrain in the UM is that scientists know there is all sorts of evidence that conflicts with their theories, but they just can’t imagine that their theories could possibly be wrong!  My interpretation, however, is that Mr. Sessions is unable to understand how any particular observation conflicts with scientific theories, because he doesn’t understand the theories (and sometimes he doesn’t even understand the observations).  The result is a sloppy string of out-of-context quotations and bizarre reasoning that brilliantly disproves all sorts of non-existent theories.

One case in point is his treatment of Plate Tectonics, the current unifying theory of geology.  First, I will explain a few basics of the ACTUAL theory.

The ACTUAL Theory

In the theory of Plate Tectonics, the “plates” (rigid slabs of rock several km thick on the surface of the Earth) move around largely because of convection currents in the mantle (the layer below the crust).

Convection is the movement of heat energy with the material it inhabits.  If you turn on the hot water faucet in your bathtub, for instance, heat energy in your water heater travels through the plumbing and into your tub because it travels with the flowing water.

Convection currents, or convection cells, move heat energy with some material in a more cyclical way.  Think of a pot of water on a stove, where the heat is actually coming from the bottom.  The water on the bottom heats up first, making it expand a little.  Since it is less dense than the overlying cooler water, the warmer water floats upward and the cooler water sinks downward.  Now the water on top is cooling off by releasing heat into the air, and the water on the bottom is heating up.  Pretty soon the water on the bottom becomes warmer than that on the top, and they trade places again.  This sets up a continuous cyclical motion.


To get convection currents, you need a source of heat on the bottom, and a way to release  the heat at the top.  You also need the convecting material to be some kind of fluid.  Usually, when we think of fluids, we think of liquids and gases, neither of which hold their shapes when they are not held in a container.  Solids are usually not considered fluids, but there are important cases where a material seems to behave like a cross between a solid and a liquid.  Think of Play-Dough, for instance.  It will keep its shape, but if you push on it with a finger, the shape is deformed.  Instead of bouncing back to its original shape or breaking, like most things we think of as solids would, it keeps its new shape.  If a solid behaves like this (i.e., it can squish around instead of cracking) then it can be moved around in slow-moving convection currents.  Rock that is heated and pressurized (but not melted into a liquid) can behave this way.

Once upon a time, it was thought that the solid crust was floating on a big ocean of magma, but since the early 20th century it has been clear that most of the Earth is solid, the only liquid layer being the outer core.  (We can tell because a certain type of seismic wave can only travel through solids.)  So if the part of the mantle underneath the plates is essentially solid, it must be softened by the heat and pressure so it can be squished around in convection currents.  These currents must move quite slowly, because plates only move laterally by a few centimeters per year.

Get it?  The plates are “floating” on top of the softened, but still solid rock below, much like you “float”, or partially sink into, your bed when you lie down on it.  (The bed is solid, but squishy.)  There is no ocean of magma (melted or molten rock) underneath.

Oh, So He Does Understand!

At some points in the UM, it seems like Sessions does understand that the “magma ocean” theory is long gone.

Ideas change. Magma was once a new idea, and as it developed, geologists imagined a great ocean of magma deep inside the Earth: an all-encompassing body that supplied the heat and lava to all volcanoes, but that idea fell out of favor during the early 1900s.  Quoting from a 1911 encyclopedia:

“The old idea of a universal magma, or continuous pyrosphere, has been generally abandoned….”  (UM, Vol. 1, p. 76)

See?  Right there in his book, Sessions tells us that it has been out of favor for over 100 years!

On the same page, it also seems clear that Sessions understands that the seismic wave evidence shows that only the outer core is liquid, even if he disagrees with scientists about what that liquid is.

Seismic waves do establish that a large portion of the interior of the Earth is liquid but it does not establish what that liquid is. A simple question one could ask is magma the only liquid found in Nature? The answer–no.

The geologists themselves state in the foregoing statement that they have only been able to “guess” what Liquid occupies the Earth’s underworld. Their research “implies a molten core” but they do not know this. They do know that there is a shadow zone caused by the liquid in the outer core of the Earth as illustrated in Fig 5.2.2. The shadow zone appears repeatedly, when earthquakes occur.

From the different magnitudes and arrival times of the different waves, researchers in the early twentieth century were able to develop a rough picture of the interior of the Earth. As technology improves, the picture is ever clearer, and one of the most convincing evidences that magma does not exist comes from an understanding about these seismic waves.   (UM, Vol. 1, p. 76)

No… He Doesn’t Understand

But just a couple pages later, Sessions makes the following claim.

The plate tectonics theory proposes crustal movement based on convective magma, one facet of the magmaplanet model. (UM, Vol. 1, p. 78)

In another chapter, he emphasizes once again that he really does believe geologists think the plates are riding around on an ocean of magma.  (He gets his information this time from… and I’m not kidding about this… a website called

It is important to note that modern geology already has empirical evidence establishing that the Earth’s Continents are floating. In fact, children are taught in grade school about floating plates, along with other not-so-proven concepts.  Here is the website, which explains how the Earth’s continental plates float:


“These plates make up the top layer of the Earth called the lithosphere. Directly under that layer is the asthenosphere. It’s a flowing area of molten rock.  There is constant heat and radiation given off from the center of the Earth. That energy is what constantly heats the rocks and melts them. The tectonic plates are floating on top of the molten rock and moving around the planet.”

We previously discussed Earth’s continental plates and their observable movement of several centimeters per year (see Fig 15.13.1), but we have taken the position that there is no magma, and therefore, no molten rock upon which the plates ride, so we naturally have to ask; what are the plates floating on? This is a truly fundamental question.  (UM, Vol. 1, p. 231)

Clearly, this is wrong, but why would Sessions cite some random geography (not even geology!) website for kids in the first place?  He cites a number of real geology textbooks throughout the UM, after all.  For example, Sessions refers several times to a book by O.M. Phillips, The Heart of the Earth, which was published in 1968, when the theory of Plate Tectonics was brand-spanking new.  Here’s what Phillips said about the issue.

Before we can ascribe any significance to this suggestion [that mantle convection drives plate motion], though, it is necessary to be convinced that movements of this kind in the mantle are qualitatively or descriptively plausible and do not do violence to the observations already established.

The idea poses an immediate dilemma.  Convection is a type of motion that can occur only in a fluid.  yet the mantle is capable of transmitting S waves, and these cannot travel through a fluid.  Furthermore, deep earthquakes occur frequently at depths between 80 and 300 km, sometimes as deep as 600 or 700 km, and sudden fracture or slipping does not occur in a fluid.  These are serious objections; are they crippling?  The answer, I believe, is no….

The simple classification of materials as solids, liquids and gases is convenient, but not particularly precise.  Some, like water at ordinary temperatures, are unambiguously liquid.  Others, like mayonnaise or the interior of a half-cooked cake are neither clearly solid nor clearly liquid….  This general type of behavior, in which the simple classification fails, is in fact very common; it is the rule rather than the exception, especially at the high temperatures that we expect to find in the earth’s mantle.  Most metals and plastics certainly behave this way.  They can be bent and squeezed into shape; they can be made to flow.  (O.M. Phillips, The Heart of the Earth.  Freeman, Cooper & Company, San Francisco, 1968, pp. 167-168)

Are you starting to get the picture?  When researching for his magnum opus, Sessions seems to have combed through hundreds of books, articles, and websites, hand-picking quotations he thought he could fit into his narrative that scientists are dogmatic and confused, and ignoring anything that might have helped him understand what scientists actually think.

There are no “magma oceans” below the crust, and no geologists I know of have thought this for a very long time.  And yet, Sessions puts quite a bit of effort into debunking this idea.  Why?




  1. I was for a number of years working with some scientist on the ancient swamp kauri of new zealand taking biscuits off the end of these logs where with Dendrochronoly and dating they established a calendar going back over 151 000 years It was established what started in 2010 so called global warming has happened 12 times before over this period of time — this so called global warming is myth and a money gathering exercise

    • Ah, so you are claiming that AGW is a scam because you started that scam off.

      Which if true is the action of a lunatic.

      And if it’s not true, then your post was the result of a lunatic raving.

      In short, this isn’t going well for you.

  2. “Sessions puts quite a bit of effort into debunking this idea. Why?”

    Straw men neither hit back nor answer back.

  3. “If a solid behaves like this (i.e., it can squish around instead of cracking) then it can be moved around in slow-moving convection currents.”

    What about treacle, too? It really doesn’t move like a liquid, does it. Pour it out and it will “puddle” but still be sitting like a blob. Cool it down and it will appear to be a solid unless you leave it for a LONG time and it will eventually puddle.

    And, though it’s now debunked, the old tale of how glass pools and forms a drop shape in the window frames of old churches because it flows so slowly?

    If the idea of semisolid is so unknown to someone, have they never seen a cowpat?

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