Transverse bar (linguoid bar)

Position: In-channel

 

Form

Mid-channel unit bar, oriented perpendicular to flow, generally found at points of abrupt channel and flow expansion points in sand-bed channels. They have a lobate or sinuous front with an avalanche face. The upstream section of the bar is characterised by a ramp which may be concave in the centre and form an arcuate shape.

 

Process description

Formed via flow divergence in highly sediment-charged sandy conditions. Flow moves over the centre of the bar, diverges and is pushed up the ramp face. Sediment is pushed over the avalanche face and deposited on the lee side. As a result, the bar builds and moves downstream as a rib.