Dust itself is nothing new. Like the circle, it is a symbol of eternal time. Long before the days of the microscope and the chemical balance it was understood that dust is the beginning and end of all things. Dust is always in the air we breate, an invisible world of tiny, buoyant particles, infinitely rich in its variety, and with laws of its own. ... The world of dust is never at rest...Two phases of his early research and writing involved dust. First, his ground-breaking book about the Dust Bowl, Deserts on the March, in 1935, for which he is best known. Second, throughout the 1930s and 1940s, his "microscopic study of those remarkable bearers of life and heredity that we call pollen," the dust of plants that tells us about times long past.
We might add a third phase, an archeological exploration in Mexico that attempted to understand the dust of human prehistory. In some ways this combined the earlier two, using the lake sediments of the Mexico City basin to untangle a story of ecological collapse more than 3,000 years old.