A pebble is a clast of rock with a particle size of 2 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are generally considered larger than granules (2 to 4 millimetres diameter) and smaller than cobbles (64 to 256 millimetres diameter). A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history. A beach composed chiefly of surface pebbles is commonly termed a shingle beach. This type of beach has armoring characteristics with respect to wave erosion...

Cobblestones are stones that were frequently used in the pavement of early streets. "Cobble", the diminutive of the archaic English word "cob", meaning "rounded lump", originally referred to any small stone rounded by the flow of water; essentially, a large pebble. It was these smooth "cobbles", gathered from stream beds, that paved the first "cobblestone" streets. In England, it was commonplace since ancient times for flat stones with a flat narrow edge to be set on edge to provide an even paved surface. This was known as a 'pitched' surface and was common all over Britain, as it did not require...