Rift Valleys as Defined by Dummies

Rio Grande Rift map

Every once in a while one of the staffers turns up an earth science-related post that just doesn't seem... right. When that happens, some hapless schmo is assigned to slip a sheet of paper with the URL under the door of the staff geologist, a personage about as curmudgeonly as they come. It's for good reason, because for some reason, freelancing J-school grads (or worse) who wouldn't touch a physics or chemistry question with a ten-foot iPad seem perfectly happy to butcher the science of the ground we stand on. One such freelancer appears to be Michael Anissimov, who vomited up "What Is a Rift Valley?" on WiseGEEK.com.

Anissimov, apparently also an employee of the site, burbled that he,

"...enjoys writing for wiseGEEK [sic] because it lets him earn money while he familiarizes himself with diverse areas of science."

Well, excuse us, geekoids, but shouldn't your "geeks" already be familiar with their topics if they're going to write "clear answers for common questions"? Whatever the case, Mike jotted down just 331 words to address this particular question. Unfortunately, most of them were... wrong. Let's get the definition of a rift valley out of the way up front:

A rift valley is a trough where a continent is splitting apart due to the forces of plate tectonics. Eventually, a rift will open far enough that an ocean basin forms between two new continents, and the rift will become an oceanic spreading center

.Anissimov's definition, however, was somewhat different. According to Michael,

"A rift valley is a geographic [sic] feature caused when one arm of a triple junction between tectonic plates 'fails' (i.e., stops spreading) and leaves a remnant canyon-like structure."

First, calling a rift valley a "canyon-like structure" is on the order of comparing a 5-year-old's tee-ball team to the Boston Red Sox. Second, that's not the definition of a rift valley, since many rift valleys are active. What Anissimov mistakenly described is what is known as an "aulacogen." Mike wasn't done yet, though, "informing" readers that,

"All of the world's largest freshwater lakes are in rift valleys, including Lake Baikal in Russia... Lake Tanganyika in Africa... Lake Superior in the United States..."

Claiming that Superior lies in a rift valley is rather far-fetched: both Baikal and Tanganyika are in tectonically active rifts. The Keweenawan rift, which in part lies under Superior, hasn't been active in almost three billion years. Our geologists submit that the relatively less resistant sedimentary rock in the trough allowed Pleistocene glaciers to gouge out the lake's basin, but claiming that it is in a rift valley? No way!

But wait, there's more...

"If the valley continues spreading indefinitely, a continent may cleave along it, ocean water rushes in, and a new mid-ocean ridge may be formed."

Water "rushes in"? Is this bozo kidding? And what about,

"...there is [a rift] right in the middle of North America, called the Midcontinent Rift System... During the Cretaceous period, 145 to 65 million years ago, this rift system was flooded, resulting in the Western Interior Seaway. This is why various marine fossils can be found in middle America today..."?

No, Mike, the presence of the Midcontinent rift was not responsible for the creation of the western interior seaway. If it had been, there would be Cretaceous sediments in Michigan's Upper Peninsula (there aren't).
More to the point, if this idiot really wanted to talk about rift valleys in North America, he completely blew it: the Rio Grande Rift zone is an active rift extending from Wyoming to Mexico, with volcanism within the past 5,000 years. You'd think our Dumbass of the Day would have come across that information in his "research"!

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