What are dust?

Terrestrial dust is mostly tiny fragments abraded from larger things. The larger things that turn to dust can be almost anything in the world, from shoes to ships to dead bodies. Wind- driven dust composed of fragments of stone and clay is so powerful that over the millennia it has cut fantastically shaped canyons and pillars in the bad lands of the American west. Drought created the dust bowl with its penetrating clouds of dry ploughed soil; the fires of ancient plains probably added to dust in teepees: soot from unburned automobile fuel plagues city apartments.

Dust knows no borders, and dust from volcanic ash lingers in the upper atmosphere to produce brilliant sunsets thousands of miles away from the eruption.