angle of repose

i read a book by wallace stegner a few years back called 'angle of repose' ... everytime i see a pile of dirt or sawdust like this one, i enjoy thinking about the term ...

from wikipedia "Explanation of the Novel's Title

The title is an engineering term for the angle at which soil finally settles after, for example, being dumped from a mine as tailings. It seems to describe the loose wandering of the Ward family as they try to carve out a civilized existence in the West and, Susan hopes, to return to the East as successes. The story details Oliver's struggles on various mining, hydrology, and construction engineering jobs, and Susan's adaptation to a hard life."
a good read, and an enjoyable, thought provoking, though only very occasionally, useful term ....