NASA's Perseverance rover has been busy gathering bits of Mars — rock cores the size of chalk sticks, clusters of broken fragments no bigger than pencil erasers, and even grains of dust fine enough to ...

The East African Rift threatens to split the massive contient into two plates in the distant future, though geological events ...

Tephra includes large, dense chunks, light rock debris, and ash ... On volcanoes, a fissure is an elongated fracture or crack at the surface from which lava erupts. Fissure eruptions typically ...

It appears to be composed of rock broken off from the moon's surface and ejected into space after a large impact. "We had a general idea that this asteroid may have come from the moon, but the ...