These formations have many names, including medial, longitudinal, crescentic, and transverse bars, as well as the more colloquial sandflat.
Alternatively, an obstacle such as a wedged log can result in the formation of a mid-channel bar if sediment is deposited along the feature.
[1] Braided rivers can have variable, erratic flows, which can lead to successive periods of greater deposition or erosion.
[1] Compared to a braid bar, an island is regarded as having a more permanent and potentially larger structure that can influence, to some degree, the path of the river.
[5] This is in part due to the nature of many braided rivers, where variable flow discharge can create a hostile environment for any significant vegetation.