Why are there so many different colours of rocks of the beach? How do they all get there?

Answer 1

Most get there by erosion. Usually the tidal action and ocean currents erode the underwater and coastal rocks. The majority of the beach is composed of coastal rocks that hasn't wandered too far from its source.

Some rocks come from the ocean and are washed up on to the shore. Other rocks get there due to wind and rivers eroding rocks inland.

Answer 2

The next time you are down at the beach, take a careful look at the nearby cliffs. Look closely at the different colors of layers and the rocks that are embedded in those layers. This will give you an idea of why so many different colors are present.

Also, many municipalities will do what they can to rebuild beaches after particularly severe storms that wash most of the beach away. To do this, hundreds of trucks filled with what is called "river wash" rocks and coarse gravels are brought in and dumpped on the beach to use as filler and a more stable base for the beach, so it doesn't get washed away in the next big storm (it hardly ever works, but they keep doing it). They then dredge sand from just offshore up on top of these rocks and rounded gravels to cover them and recreate the beach that had washed away.

Now the rocks they bring in wash down rivers from many different geologic environments and these rocks get smoothed and rounded as they tumble along. Coming from many different geologic environments, gives them their many different colors and textures.