why are stones in a river smooth, but rocks near the ocean jagged and irregular?

Question

Water should smooth out eventually the rocks by the sea or am I wrong?

In: 2

Answer 1

It’s all about the flow of water and how that erodes the rocks.

If you think about it, a river tends runs smoothly in a single direction which would wear something down rather uniformly.

The ocean, on the other hand, is much more tumultuous and waves breaking can wear rocks in more unpredictable patterns (splashing up against, then rising upwards and outwards). The tides and currents can also vary the direction wave breaks.

If you try to visualize it you can almost see how it would happen like this.

Further, they way erosion occurs also depends on the mineral type(s) of the rocks themselves and how porous they may be. Salt and sediment content of the water also plays a role.