Question

1. explain abrasive action and how it contributes to the shaping of a river channel.

Explanation:

Abrasive action (corrasion) in rivers is when river - carried materials (like rocks, pebbles, sand) rub against the river channel (bed and banks). As the river flows, these materials are transported and scrape the channel surfaces. Over time, this wearing - down process deepens the river bed (vertical erosion) and widens the banks (lateral erosion). For example, in a rocky riverbed, the constant abrasion from pebbles can create smoother, deeper channels, and also erode the banks to form features like river cliffs or widen the floodplain over long periods.

Answer:

Abrasive action (corrasion) occurs when materials (rocks, pebbles, sand) carried by a river rub against the river’s bed and banks. This action erodes the channel: it deepens the bed (via vertical erosion) as materials scrape the riverbed, and widens the banks (via lateral erosion) as they abrade the bank surfaces. Over time, it shapes the river channel, creating deeper, smoother beds and wider banks (e.g., forming river cliffs or widening floodplains).