How are ravines formed?

Let’s follow the raindrops falling to the ground. On the way, we climb the mountain. A warm rain has started. Its rare, large drops fall heavily on the loose ground. Bend down. You will see pits that rain drops leave behind.
Suddenly the rain began to fall heavier, and the drops are no longer absorbed, but flow down in tiny streams. Stalks of dense grass stand in their way. They break the streams into parts, prevent them from merging into larger streams. Even a heavy downpour is powerless to destroy the soil surface in areas of dense grass.
And now we will find a place on the slope where there is no green grass and loose rock lies right on the surface. Here the raindrops deepened, made a gully.
Each subsequent rain deepened and lengthened this ravine. Gradually the gully stretched across the entire slope. So the ravine appeared. They are formed as a result of the activity of flowing waters.