Over time, the horns and thorns of the stones in the river have been washed round. How to understand?

This problem involves a phenomenon in nature, that is, the stones in the river are washed away by the current and become smooth. This phenomenon can be explained from the following aspects.

First of all, the water in the river has an impact force, especially where the water flows fast. When the water hits a stone, the impact force will be great. This impact will gradually wear off the sharp edges and corners of the stone surface and eventually become smooth.

Secondly, there are also some entrained and suspended sand grains in the current. These particles will physically collide with the stone surface under the scouring action of water flow, causing the stone surface to wear. Over time, this collision will make the stone smooth gradually.

Finally, the passage of time is also an important factor leading to the rounding of stones. The scouring process in rivers is a long process. With the accumulation of time, the sharp corners and edges on the stone surface are gradually worn away and finally become relatively smooth.

To sum up, with the passage of time, the scouring effect of water flow and the physical collision of particles make the stones in the river smooth.