Boulder berm (boulder bench)

Position: In-channel

 

Form

Elongate, bank-attached stepped feature inset against the bank. Can have a convex cross-section. Comprise coarse, boulder bedload materials with limited finer grained matrix.

 

Process description

Formed from bedload deposition in a single event under high velocity conditions. Materials are accreted (or dumped) along the bank where flow velocity decreases substantially. Reworking is restricted to subsequent high velocity events that have the competence to mobilise the boulders.