small white pebbles for garden

rock soil stonewall asphalt flooring gravel pebble cobblestone rubble sand floor boulder monochrome geology wall wood brick small white pebbles garden clast particle size 4–64 0 16–2 52 based udden-wentworth scale sedimentology generally considered larger granules 2–4 0 079–0 157 diameter smaller cobbles 64–256 2 5–10 1 diameter termed conglomerate tools earliest man-made artifacts dating palaeolithic period human history