Mogul (skiing)
Moguls are bumps in a ski slope formed when skiers cut grooves in the snow as they execute turns.
Once formed, a mogul tends to grow, as skiers will follow similar paths around it, further deepening the surrounding grooves. Since skiing tends to be a series of linked turns, moguls form together.
In most ski resorts certain pistes are left un-pisted (un-groomed) to allow moguls to develop.