  Experimental observation of a new mechanism of sandpile formation is
reported. As a steady stream of dry sand is poured onto a horizontal surface, a
pile forms which has a thin river of sand on one side flowing from the apex of
the pile to the edge of its base. The river rotates about the pile, depositing
a new layer of sand with each revolution, thereby growing the pile. For small
piles the river is steady and the pile formed is smooth. For larger piles, the
river becomes intermittent and the surface of the pile becomes undulating. The
frequency of revolution of the river is measured as the pile grows and the
results are explained with a simple scaling argument. The essential features of
the system that produce the phenomena are discussed.
