"Soil is formed by water".

Yes, "action of water in weathering" (wetting and drying, frost action, abrasion).

1. Wetting and Drying. Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.

2. Frost Action. Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation.

3. Running water carrying rock fragments would break and grind rocks occurring in the pathway. Rain and hail also cause rock breaking.