Convergent Boundaries for Dummies, the Rewrite - The Freelance Files MMCCIV

Continental island arc with trench

For some bizarre reason, a not-insignificant segment of scientifically illiterate society seems to think that the mere possession of any degree that includes a "science" designation makes one an expert on all aspects of all science. This rather strange notion is, apparently, the logic behind the recent appearance of the byline, "Reviewed by: [name] M.Sc. [discipline]" on posts at Leaf Group's Sciencing.com. Staffers who've written peer-reviewed articles, which this pretends to emulate, note that the reviewer is always someone with an advanced degree in the science at hand. That's not, however, the case in "Facts on Convergent Boundaries" as rewritten by Meg Schader and reviewed by Sylvie Tremblay, with a degree in "Molecular Biology and Genetics."

Shader's post is a rewrite of an execrable bit of pseudo-science originally penned by history grad Cathel Hutchison. Although Meg ostensibly has a science degree ("MPS in 'environmental studies'"), the topic clearly lies outside her area of expertise; as well as that of her reviewer. As a result, Shader's content is rife with misleading statements and semi-accurate factoids. We've compiled a few examples of the post's shortcomings:

• "Tectonic plates... float on the layer below... and the continents move with them." – Meg must not have remembered that there are also oceanic plates that contain no continental crust.
• "Pangea... existed between 300 and 100 million years ago..." – Most geologists call the supercontinent "Pangaea," but that's a mere quibble. Meg's problem here is that the breakup of Pangaea began at the end of the Triassic, about 225 million years ago.
• "Interesting [sic] things happen at the boundaries of these tectonic plates, including earthquakes, volcanoes, mountain range formation and hot spots [sic]." – Meg's obviously misinformed about hotspots (more on that later)...
• "Subduction is... when one tectonic plate moves below another plate. Essentially, the cooler of the two plates sinks under the warmer tectonic plate, and the lower plate melts back into the mantle of the earth." – A) She meant "denser," not "cooler"; and B) the lower plate doesn't "[melt] back into the mantle," the heat (and pressure) at depth cause the subducted plate to melt.
• "At ​oceanic-oceanic convergent boundaries​, two tectonic plates converge and form an oceanic trench..." – ...not to mention an island arc. Oh, and trenches form where an oceanic plate subducts beneath a continental plate, too.
• "As the subducted plate at a convergent boundary returns to the Earth's mantle, heat is transferred upwards to the crust and can become a volcano." – Heat "becomes a volcano"?????

• "The places where magma rises from the Earth's mantle are called ​hot spots​ [sic]..." – No, the places where magma rises are called "magma chambers," and volcanic arcs (usually) lie above them. A hotspot is something entirely different.
• "...since tectonic plates are constantly shifting, sometimes the movement of plates causes volcanoes to move away from hot spots [sic]." – Well, yeah: but hotspots are not at plate boundaries... for instance the Hawaiian Islands lie above a hotspot in the center of the Pacific (3,000 miles from the edge), and Yellowstone lies above a hotspot within the North American Plate.

Although Shader didn't seem to understand hotspots, current thinking is that they mark locations where anomalously hot mantle rises to the bottom of the crust (mantle plumes).  They are not the locations of volcanic arcs.

Neither author Shader nor reviewer Tremblay (a "genetics researcher-turned-freelance writer") knew enough about the topic at hand to correct Hutchison's errors and avoid making their own. For their troubles – and for their unhelpful rewrite of Cathel's junk – we do hereby give them a team Dumbass of the Day award.

SI - TECTONICS