Contour Maps for Dummies

It's not always elevation, Lindsay!

Our staff geologist (yes, there is one) spent many years working in the petroleum industry, where a former boss introduced him to the nickname, "the contour factory." In olden days, geologists (and geophysicists) spent their days drawing contour lines: they'd generate contour maps of structure, thickness, porosity, permeability, even esoteric measurements like gamma ray maximum. If only WiseGEEK.com had asked someone like our staff geologist, "What Is a Contour Map?" Unfortunately, however, they asked Lindsey Rivas.

We've noticed as we delve deeper into the content at WiseGEEK that it's typical for the chosen freelancer to generate a polished article that goes into some depth. The site doesn't include references, but it's generally pretty clear that their freelancers grab an authoritative article and massage it for all its worth. In the case of the "contour" article, Rivas immediately exposed her unfamiliarity with contour maps by zeroing in on a specific type of map instead of the accepted general definition of the term:

"A contour map, sometimes called a topographic map, is a representation of a three-dimensional feature using contour lines on a flat surface. "

Oh, sure, that's right – for topographic maps. Unfortunately for Lindsey, not all contour maps are topographic maps. She's done the equivalent of equating all trucks with the White Freightliner: there are a lot of other trucks – and contour maps – out there.
Even one of Lindsay's sycophants (WiseGEEK's in-house commenters) seemed to be aware that there are other kinds of contour map:

"I think I'm mostly familiar with contour weather maps. I know, in that context, the lines are called isobars..."

Therein lies Rivas' failure: the prefix iso-, which means "equal," is often found describing contour lies that have nothing whatsoever to do with elevation. Some examples include isobar, isochron, isopach, isobath... The best our candidate can do with that concept is her throwaway closing paragraph (apparently an afterthought):

"Although a contour map is often used to map geographical features such as elevation, it can have other purposes as well. For example, in meteorology, this type of map often is used to show temperature or precipitation. Another example is when geologists use contour maps to show the depth of a lake or even underground features."

Wow: it "can have" other purposes... Just because the only contour map Rivas had ever seen when she wrote this – if she'd ever seen one at all – was a topographic map certainly does not mean that all other contour maps should be relegated to an afterthought by our Dumbass of the Day.

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