AÃÂ pebbleÃÂ is aÃÂ clastÃÂ ofÃÂ rockÃÂ with aÃÂ particle sizeof 2 to 64 millimetres based on theÃÂ Krumbein phi scaleÃÂ ofÃÂ sedimentology. Pebbles are generally considered larger thanÃÂ granules& x28;2ÃÂ to 4 millimetres diameter& x29; and smaller thanÃÂ cobblesÃÂ & x28;64ÃÂ to 256 millimetres diameter& x29;.ÃÂ