Final answer:
Slow-moving zig-zagging rivers create floodplain valleys, characterized by wide, flat areas where the river deposits sediment as it meanders.
Step-by-step explanation:
Slow-moving zig-zagging rivers tend to create floodplain valleys. These rivers meander across wide, flat valleys, depositing sand and silt as they snake along, which can result in a triangular-shaped land known as a delta.
This process contrasts with faster-moving rivers, which typically carve narrow, V-shaped valleys or, in the case of valley glaciers, which flow downward between the walls of valleys creating U-shaped valleys. Floodplain valleys are often found in the lower parts of a river where the water flow is more tranquil, allowing for the deposition of sediments.