Geoscientists have for the first time revealed the magma plumbing beneath Mount St. Helens, the most active volcano in the Pacific Northwest. The emerging picture includes a giant magma chamber, between 5 and 12 kilometers below the surface, and a second, even larger one, between 12 and 40 kilometers below the surface. The two chambers…

There’s diamond under them thar plants. A geologist has discovered a thorny, palmlike plant in Liberia that seems to grow only on top of kimberlite pipes—columns of volcanic rock hundreds of meters across that extend deep into Earth, left by ancient eruptions that exhumed diamonds from the mantle. If the plant is as choosy as…