Toe erosion with upper bank failure is often observed along the outside of bends. The main indicator of this type of bank erosion is the presence of discrete blocks of failed bank material, often with upper bank vegetation still intact, along the eroding bank toe. Occasionally undercut regions may be observed along the bank, with sections of upper bank tenuously held in place cantilever-fashion. These cantilevered sections tend to fail readily. Tension cracking may be observed along the top bank, with cracks running parallel to the bankline. After failure, blocks of upper bank material provide some protection for the eroding toe until it they are washed away, and then the process of toe erosion and upper bank failure is repeated. Failure blocks along the bank toe, often with vegetation still intact on the top surface are often observed when this type of erosion is present. Sharp bends tend to cause strong secondary currents that attack the outer bank toe just downstream of the bend apex, which may result in toe erosion with upper bank failure. Incised channels, which typically have abnormally high banks, often feature a combination of general bank instability and toe erosion with upper bank failure, which creates steep bank angles.