What is the formation of pebbles of decorative gravels

About 100 million years ago in the Mesozoic, the role of movement in the crust, the magma emitting surface, glow in the dark stone , rapid cooling of the magma is formed of granite. After thousands of years ago, due to the granite magma intrusion caused dislocation extrusion, resulting in a large number of smaller stones, those stones at the water's edge, decorative aggregate after each rolling long period of slow water erosion and the formation of today's final, pebbles.