President Obama today announced his intention to name Marcia McNutt as the next head of the U.S. Geological Survey, the world's foremost Earth science agency (see the announcement at whitehouse.gov). This will be a nice change, as McNutt has actually served in the USGS unlike her two predecessors Charles Groat and Mike Myers. The 15th USGS chief in its 130-year history, McNutt will become the first woman to head the agency. In addition, she will become the Science Advisor to the Secretary of the Interior, a position never previously occupied by the USGS head, or indeed by a geologist (three previous advisors were biologists).

Washington will be a wrenching change from Moss Landing, California, where McNutt heads the Monterey Bay Aquarium Research Institute (MBARI). She is brilliant, tested, and well connected, and I wish her the best.

About the USGS
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Biographies of women geologists

If you get into geology, even as an amateur, you also need to learn about the outdoors. The wonderful mountains of Southern California are prone to landslide, fire and flash flooding, but they also harbor a dangerous plant with the innocuous name of poodle-dog bush. Learn more about Turricula parryi in the Hazardous Plants Gallery. Fortunately its range doesn't overlap that of the teddy-bear cactus. Thanks for this to my online friend Jon Carroll, whose daily column is sometimes useful as well as always entertaining.

Komatiite is one of Earth's weirder rocks. It has the composition of the mantle rock peridotite, but it was clearly a molten lava—something that would have taken several hundred degrees more heat than Earth is capable of today. That's why komatiite is almost exclusively confined to the Archean Eon, from the first half of Earth history when radioactive heating was greater. And yet in many places it displays this hashwork of long olivine crystals known as spinifex texture.

Crystals usually take a long time to grow so big (as much as a meter in length), much longer than a lava flow would allow. The usual story is that the lava must have been both superheated and supercooled, so that these things crystallized in a flash. The story goes on to say that the lava must have been as fluid as water, plus other outlandish details. An outlandish story can be plausible for sound reasons. But recent papers in Nature and in the Journal of Petrology point instead to a very steep thermal gradient that encouraged olivine to grow so oddly: the thin crystals acted like heat pipes, transmitting heat by both conduction and radiation. Maybe the story will become a bit less outlandish—or outlandish in different ways.

More igneous rock types
More igneous rock textures
More on the Archean

Spinifex texture — Photo courtesy Mayla Oliveira of Flickr

In the Geology Forum today, I acknowledged a correction to something erroneous I'd written: "None of you should be shy about correcting me. There is so much to know, and I am only grateful for the help. An important attribute of a scientist (and writers too), no matter what your field, is readiness to admit error. At the same time, advancing a new idea requires a large degree of self-confidence. The mental discipline it takes to achieve both can be quite demanding."

At a higher level, in its July 4 issue Science News published an exchange between award-winning science students and some Nobelists. The questioner asked what the Nobelists would do if their theories were proven incorrect. Leon Lederman noted that a key feature of science is that "we know how to fix things when they are wrong." Martin Chalfie said that being wrong "is how we work normally." Dudley Herschbach explained that being wrong "is part of science, so you don't fear being wrong." More worthy responses are in the article.