Pebble formation process

It can be river scouring or mutual friction. The pebbles may be caused by historical floods and mudslides (generally in mountainous areas), but the specific reason depends on the geological structure and geographical environment there, as well as the conditions of other surrounding mountains. In the Mesozoic era about 100 million years ago, under the action of crustal movement, magma emerged from the earth's surface, and rapidly cooled magma formed granite. Since then, thousands of years ago, due to the intrusion of magma, the granite staggered and squeezed, resulting in a large number of smaller stones. Those stones near the water, after a long period of slow water erosion and their own rolling, finally formed today's pebbles. Some are rounded and become cobbles after weathering