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Popular Week of January 5, 2018

Nothing is clear about who left marks on ancient bones

An ongoing debate regarding the origin of scrape marks on ancient animal bones has taken a new turn. The marks were first thought to have been made by early hominid butchers, then by trampling, and now it’s looking like crocodiles might have been responsible, according to a recent study in Proceedings of the National Academy of Sciences (PNAS).
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pyrometamorphism

pyrometamorphism (py''-ro-met''-a-mor'-phism). (a) Metamorphic changes taking place without the action of pressure or water vapor, at temperatures near the melting points of the component minerals; it is a local, intense type of thermal metamorphism, resulting from the unusually high temperatures at the contact of a rock with magma, e.g. in xenoliths (Turner, 1948). Cf: igneous metamorphism. (b) "Metamorphism" caused by lightning strikes and burning coal seams.

Critical Minerals

By Lindsay Davis, GSA Science Policy Fellow

The legislative and executive branches are taking steps to decrease what President Trump calls a “strategic vulnerability” brought about by U.S. dependence on imports for certain non-fuel mineral commodities. These commodities, known as “critical minerals”, are vital to the U.S. economy, national defense, and other technology, and exist in limited quantities around the globe. According to a report published by the United States Geological Survey (USGS) on December 19, there are currently 23 critical minerals upon which the U.S. relies to support the military and technology development, many of which are imported either partially or exclusively from other countries, meaning their supply could be disrupted.

Cover of the report released by the USGS in 2017 on critical minerals. Credit: USGS.

S-type granitoid

S-type granitoid . A granitic rock produced by magma derived from partial fusion of metasedimentary or supracrustal origin. The term, proposed by Chappell and White in 1974, is thoroughly discussed by Clarke (1992).

More good news to start 2018: 2017 was the safest year on record for air travel.

Continuing the good-news theme of recent LOTRW posts, the flight safety story lit up yesterday’s internet. This report, from Fortune’s website, gives the flavor:  Airlines recorded zero accident deaths in commercial passenger jets last year, according to a Dutch consulting firm and an aviation safety group that tracks crashes, making 2017 the safest year on record for commercial air travel.

Dutch aviation consulting firm To70 and the Aviation Safety Network both reported Monday there were no commercial passenger jet fatalities in 2017. “2017 was the safest year for aviation ever,” said Adrian Young of To70.

To70 estimated that the fatal accident rate for large commercial passenger flights is 0.06 per million flights, or one fatal accident for every 16 million flights.

The Aviation Safety Network also reported there were no commercial passenger jet deaths in 2017, but 10 fatal airliner accidents resulting in 44 fatalities onboard and 35 persons on the ground, including cargo planes and commercial passenger turbo prop aircraft.

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