Final answer:
The smaller channels that a major river channel splits into at the head of a delta are known as distributaries. They carry water and sediment from the river into the sea, forming deltas that are rich habitats for wildlife and fertile land for agriculture.
Step-by-step explanation:
At the head of a delta, the major channel splits into smaller channels that follow different paths to the sea. These smaller channels are known as distributaries.
A delta is an often triangular-shaped section of land formed as the waters of a river slow down and split into many channels as they deposit sand and silt that has been carried downriver. When a river reaches the ocean, the water typically slows dramatically and any silt in the river water will settle, creating the delta. Deltas are low-elevation areas of sand and mud, formed as the silt settles onto the ocean bottom, especially in places where the sea has minimal currents and wave action.
On Earth, these features are essential as they often create rich habitats for wildlife and are fertile grounds for agriculture due to the sediments they carry. For example, after major flooding or other events that lead to high volumes of water flow, some rivers can divide into multiple distributaries before reaching the sea, which may later reconnect or evolve over time into separate channels entirely.