In terms of erosion, which letter displays the word meander?

Letter S displays the word meander because letter-S channel pattern fashioned in alluvial materials by erosion of the concave bank, which is free to shift its location and adjust its shape as a part of a stage in migratory movement of the channel as a whole down an erodible, alluvial valley. A meander is characterized by curved flow patterns and alternating shoals and bank erosion.