UW News
Fang-Zhen Teng
June 13, 2016
Arc volcano releases mix of material from Earth’s mantle and crust
![black rock and green rock](https://uw-s3-cdn.s3.us-west-2.amazonaws.com/wp-content/uploads/sites/6/2016/06/04152505/volcano_1342-150x150.jpg)
Rock from a common type of volcano shows surprising evidence of the descending tectonic plate. Analyses show that magnesium atoms are somehow drawn out of the crust, deep below the surface.