A striking photo fills most of the space above the fold in today’s NYT science section. Two men with impressive hardware are on a steep slope of boulders and scree. Just a few months earlier the spot was fiercely on fire. What is striking is not the story’s topic – debris flows – but how quickly plants, shrubs, and trees are sprouting bright verdant foliage. Nature can be killed – but it’s not easy. The story beneath it by Henry Fountain takes readers along as the men gather data in Southern California that will be useful in understanding when and why such slopes may fail in the rain.

To these eyes a small sentence is a key point: the locale is “..a likely place for a landslide – in this case, more properly called a mudslide, or, even more properly, a debris flow.”  That’s true. It’s a good tale, colorful and exact in most respects. But it should reflect the lesson it just related. He should have switched to the proper term for the rest of the way. The different words dissect key differences among phenomena the public and media often conflate and that this story does not clarify.

The headlines and text several times refer to landslides, but tellingly the experts in their quotes call them debris flows.  And debris flows and mudflows are apparently their prime concern – hazards that start with runoff and dig away at burned slopes from the surface down. They can spawn dangerous torrents of glop, tree trunks, and boulders with enough force to sweep away houses and enough speed to catch a running person. Although such flows are broadly in the landslide category, the classic landslide does not appear to be the study’s concern. These often occur well after the rain stops. They tend to be deep-seated blocks of hillside that begin to move as infiltrating water adds weight and lubricates a contact with still-deeper units. They may move  rather slowly at first. When geomorphologists get together they don’t often say landslide when they mean debris flow. They hardly ever say mudslide. It doesn’t slide. It flows. As I’ve said before, you can slide a turkey but you can’t slide the gravy.

The Tracker is writing this from memory, a dangerous practice, but is pretty sure of it. And it also seems likely that the very process Fountain correctly identifies as a hazard – hydrophobic near-surface layers that intensify runoff and thus the danger of debris and mud flows – might well help prevent genuine landslides later and that are due to deep soaking and loading of hillsides. Fountain is, as one must hasten to say again, a terrific writer – as seen in his pieces written for this week’s collection of Observatory shorts (on whiskers, on fabric and sun damage, and on the taste of carbonation ) .

Oh boy, too much time spent on that picky excursion into usage and definitions.

Other headlines to note:

• Donald G. McNeil: Flu Story: A Pregnant Woman’s Ordeal ; This needed writing. Pregnancy and swine flu are a bad mix. Get the shot if  you’re carrying. The story doesn’t mention comic Bill Maher and his high profile ill-founded insistence the flu is no big deal and that the shots are too dangerous, but it surely was on McNeil’s mind. His story serves to counter paranoid and ideological nonsense on this issue.
• Sean B. Carroll: Remarkable Creatures . For Fish in Coral Reefs, It’s Useful to Be Smart ; Fine piece of escapist (ie no extinctions, sea levels, budget woes, or idiot policy news) science writing by a well known biologist and science popularizer.
• Nicholas Wade: Researchers Create Artificial Memories in the Brain of a Fruitfly ; Illus reproduced here to express condolences to Wade and to the artist who made this image for Nature. The Times put it on a black and white page for the print issue. Alas.
• John Markoff - Rethinking What Leads the Way: Science, or New Technology? ; A review of a book that turns on its head one notion of how science and technology interact.

Also in NYTimes:

• Leslie Kaufman: Nudging Recycling From Less Waste to None ; On line yesterday, p. 1 today; “None” is too strong a term, but some places have found a way to stop filling the conventional trash cans. Towns with landfills near capacity, and their residents, ought to take some notes off this piece.

As usual, much more.  ; Whole Section.

- Charlie Petit

This entry was posted on Tuesday, October 20th, 2009 at 12:40 pm and is filed under Environment & Energy Stories, Health & Medicine Stories, Science Stories. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.