These bars occur in relatively straight sand-rich channels parallel to the flow direction. Longitudinal bars often form in braided channels where the gradient is insufficient to transport the sediment. The horizontal stratification is well developed, and accretion builds up the material on the margins. Downstream deposition is characterized by low and moderate angle cross stratification.
Longitudinal, transverse & lateral migrating bars Galloway, W. E. and D. K. Hobday.
Terrigenous Clastic Depositional Systems.
Springer-Verlay New York, Inc., New York, 1983.