xOoids : Small (< 2 mm), spheroidal, layered sedimentary grains, usually composed of calcium carbonate, but sometimes made up of iron- or phosphate-based minerals.
Glaciovolcanoes, they're called, these rumbling mountains where the orange-red fire of magma meets the frozen blue of glaciers. Iceland's Eyjafjallajökull volcano, which erupted recently, is but one of...Read more