The angle of repose of wheat...

is about 27 degrees to the horizontal as demonstrated by these piles of grain outside an elevator. This critical threshold describes the maximum stable slope that a dry, loose granular material can assume and is primarily a function of the grain size of the material involved. This concept is employed by geologists when assessing the stability of natural slopes.

Grain elevator near Ritzville, Washington. It’s been quite a good yield despite the dry conditions this year in the Columbia Basin.