Braid bars, or mid-channel bars, are landforms in a river that begin to form when the discharge is low and the river is forced to take the route of less resistance by means of flowing in locations of lowest elevation. Over time, the river begins to erode the outer edges of the bar, causing it to become a higher elevation than the surrounding areas. The water level decreases even more as the river laterally erodes the less cohesive bank material resulting in a widening of the river and a further exposure of the braid bar. As the discharge increases, material may deposit about the braid bar since it is an area in the river of low velocity due to its increased elevation in relation to surrounding areas. During times of extremely high flow, the bars may become covered; only to resurface when the flow decreases. Most braid bars do not remain stable or in one location. However, vegetation succession on braid bars can increase the stability of the landform. They are commonly composed of sand or gravel and typically occur in braided rivers.