A
mouth bar is a
bar in a
river that is typically created in the middle of a
channel in a
river delta. It is created by a
positive feedback between mid-channel
deposition and flow divergence. As the flow diverges near the
ocean,
sediment settles out in the channel and creates an incipient mouth bar. As flow is routed around the incipient bar, additional sediment is deposited on the incipient bar. This continued process results in the formation of a full-fledged mouth bar, which causes the channel to
bifurcate. This continued process leads to the characteristic
fractal tree pattern found in some
prograding river-dominated deltas.