Point bar

A point bar is a depositional feature made of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope.

Due to their near flat topography and the fact that the water speed is slow in the shallows of the point bar they are popular rest stops for boaters and rafters.

However, camping on a point bar can be dangerous as a flash flood that raises the stream level by as little as a few inches (centimetres) can overwhelm a campsite in moments.

[2] This movement of the boundary layer is capable of sweeping and rolling loose particles including sand, gravel, small stones and other submerged objects along the floor of the stream toward the point bar.

The pressure gradient is capable of driving the boundary layer up the shallow sloping floor of the point bar, causing sand, gravel and polished stones to be swept and rolled up-hill.

The eroded material is swept and rolled across the floor of the stream by the secondary flow and may be deposited on the point bar only a small distance downstream from its original location in the concave bank.

An old fallacy exists regarding the formation of point bars and oxbow lakes which suggests they are formed by the deposition (dropping) of a watercourse's suspended load claiming the velocity and energy of the stream decreases toward the inside of a bend.

In a steady-gradient section of a watercourse, sedimentation may occur where the water is saturated and the shallow bank has high flow resistance but does not agitate the suspension.

These materials have not been carried in suspension and then dropped on the point bar – they have been swept and rolled into place by the secondary flow that exists across the floor/bed in the vicinity of a stream bend, which will be intensified if there is reflection particularly from an irregular, scoured opposing bank.