A Layered Earth for Dummies

crust, lithosphere, mantle, and asthenosphere

For whatever reason, the official search-engine optimization (SEO) guru at Demand Media Studios¹ insisted that the optimal content size be 300 to 500 words. While some questions (the meat and potatoes of the flagship DMS site, eHow.com) could be reasonably answered in such a space, others could not. Today's DotD goes to an eHow.com contributor, Jean Asta, who we caught introducing dumbassery to pad the simple answer to the question, "What Is the Difference Between the Crust & the Lithosphere?"; which now appears at Sciencing.com. Ick: we hate that name...

Asta chose a question that could have been answered in far fewer than the 528 words she needed to meet that all-holy minimum word count. In fact, she (more or less) answered it completely within the first two sentences when she said,

"The lithosphere is not an individual layer, but rather a zone made up of two of the layers of the Earth, which includes the crust."

In fact, the lithosphere comprises the crust and the uppermost, brittle portion of the mantle. Easy-peezy, lemon-squeezy, right? And if Jean had stopped there, she would have been... well, OK – not necessarily "right," but OK. Asta, however, had to keep writing; which is where she came up with the scientifically illiterate rubbish that so often afflicts eHow's stable of English Lit graduates. Some (although not all) of her dumbassery follows (with corrections):

• "The core, the innermost layer, is rich in iron and very dense." – "Rich" in iron? It's a nickel-iron alloy.
• "The mantle is made up of molten rock called magma." – No, it isn't. Magma is melted lithosphere. Why can't those liberal arts graduates ever figure that out? That's not to mention that the word "magma" appears in none of Asta's references...
• "[The crust] is the thinnest layer of the Earth at only 60 to 70 kilometers thick..." – No, Jean, oceanic crust is generally 5-10 km thick while continental crust is 30-50 km thick.
• "The crust surface is shaped by characteristics of the lithosphere that cause formations like mountains and fault lines." – No only is that rubbish ambiguous, but that's not what "formation" means to a geologist.
• "Volcanic activity occurs at subduction zones and forms continental landmasses..." – Not to put too fine a point on it, but volcanic activity occurs at just about any plate boundary and quite a few other places as well.

Now, if Asta had left well enough alone and just gone ahead and said words to the effect of "The lithosphere includes both the crust and the brittle upper mantle," she wouldn't be getting another Dumbass of the Day award. But she had to go and write another 500 words, about half of them bogus...

¹ now known as Leaf Group

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