San Gabriel River Cobble Granite river rock Southern California River Rock Quarry Similar in color to Sierra River Rock but with more colors and rounded material. This hard granite rock is quarried from the river beds and washes that were once seasonally flooded by the waters flowing out of the San Gabriel and San Bernardino Mountains. This river rock cobble is a mixture of rounded and angular material that is mostly made up of colors of silver, grey, some tan and lesser colors. This rock is sold in bulk and in palleted wire baskets.
San Gabriel River Rock is available in the sizes:
2" to 4" 4″ to 8″ 9″ to 12″ 12 to 18"
There are also large to huge boulders in this rock.