Convection Currents, the Dummy Explanation

Convection currents in the mantle

It's hard to answer a stupid question, even if you know a lot about the subject. It's far more difficult to answer a stupid question if you don't know jack about the topic, though one well-known website built a veritable empire out of paying people to do precisely that. The website, of course, was eHow.com. Today we'll examine the contribution of Iris McCammon, who – though she probably couldn't find a volcano if one were to start leaking lava in her closet – still discussed (and we use the word loosely) the topic "Convection Currents in Volcanoes" for the nice people at eHow, who then moved her work to Sciencing.com,

The question is stupid to begin with, because convection currents aren't found "in" volcanoes; the relationship between the currents and volcanism is a great deal more complicated than that. That complexity, however, didn't keep Iris from spreading a little misinformation; beginning with her introduction:

"...convection currents... are repetitive actions that occur underground. As pressure builds beneath the surface of the Earth, it pushes rock sediments upwards, releasing molten rock." "...repetitive actions that occur underground"? Is this moron kidding? But no, McCammon has even more dumbass stuff to say on the topic (gotta meet that minimum word count): "Volcanic convection currents are the reactions to the heat energy within the Earth's core causing a repeated rise and fall of Earth's properties... The constant heat causes the same cycle to happen over and over, as convection currents push the liquid material in the volcano's tube toward the Earth's surface."

Let's see what Iris has to say about plate tectonics:

"As convection currents reach the mantel [sic], the heat causes a collision between the continental plate and the oceanic plate under water. The collision causes the two plates to converge, which means that the ocean plate slides downward at a 45 or lesser degree angle. The convection current continues to push the heated magma past the mantel level, reaching the crust of the Earth's surface and producing a lava spout."

Oh. My. God. That kind of stupidity makes our head hurt... and she can't even spell "mantle" right! But wait! There's more!

"Convection current movements create a push and pull effect, creating the volcanic trenches, which are formed when two plates collide. The friction between the plates cause one to melt, forcing the other to move downward and leaving a gap."

Apropos nothing, Iris suddenly shifted to shield volcanoes. Feast your eyes on the sort of moronic bullshit she produced for this section of her post:

"Hawaiian volcanoes are shield types, which are flat dome-like shapes with characteristics of calm eruptions. This is the case because the extruded lava is a steady cascade, producing fluid lava flows in stark contrast to an explosive release of lava by other volcanoes. The texture and consistently of the lava allows it to travel over long distances"

OK, enough of that sort of crap. a brief overview of the relationship between convection currents and volcanoes would actually look something like this:

Convection currents are vast, slow-moving currents within the asthenosphere, the semisolid portion of the earth's mantle. These currents allow transfer of the latent heat of the core. Hot, relatively light rock at the base of the mantle slowly rises until it reaches the base of the lithosphere, the solid portion of the mantle, at which point it's become cool enough to start sinking again. This creates a painfully slow circular motion of the rocks in the asthenosphere. There are lots of convection cells. The solid rock nearer the earth's surface gets slowly dragged in different directions by the circulation of those many cells, which has the effect of pushing around huge blocks or plates of the planet's crust. Where two plates are pushed together, one (usually) slides under the other. When it gets deep enough, it melts and the liquid rock (called magma) v-e-r-y slowly rises to the surface. If any magma makes it all the way to the surface, it creates a volcano. That's called "convergence" - an example of volcanoes created this way is the volcanoes in Japan and Indonesia. Where two plates are pulled apart, hot mantle rocks sort of bubble up (again, v-e-r-y slowly). This "divergence" also creates volcanoes, like those in Iceland. In a few places, the heat of the rising convection current melts the underside of the crust and creates still another kind of volcanoes. A well-known example of the "hot-spot" volcanoes caused by such mantle plumes is the Hawaiian Islands.

That's pretty what Iris McCammon could have said if she'd worked at it for a few more minutes. Instead, she spread around the bull -- and that's why she's the Antisocial Network's Dumbass of the Day.

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