Wave currents occur in a swash and backwash motion. Used backwash water contains high concentrations of particulate material. Beach steps form where the backwash interacts with the oncoming incident wave and generate vortex. Swash consists of two phases&colon; uprush (onshore flow) and backwash (offshore flow). The backwash from the wave formed channels by rearranging the boulders. A barrier was proposed to counteract the backwash of the Ouse into the River Foss. Generally, uprush has higher velocity and shorter duration than backwash. The backwash system can be optimized using IPC membranes, as developed by Blue Foot Membranes. The backwash of the Investiture controversy had left the German states in continuous turmoil. The shape is also designed to withstand the backwash from a tsunami. It defeats Malco but the backwash nearly demolishes the monastery. Saxon loses her baby in the backwash of the violence. Backwash and sidewash also sometimes form in conjunction with rips on beaches. He praised Valo's performance, but criticized the material backing him as "dull" and "turgid backwash". People with backwash ileitis might have an increased risk for colorectal carcinoma.