What is Pebble?
[[File:Pebbleswithquarzite.jpg|right|thumb|230px|Pebbles on a [[shingle beach]] in [[Somerset]], England]] [[File:Pebbles on beach at Broulee -NSW -Australia-2Jan2009.jpg|right|thumb|230px|Pebbles on a beach at Broulee, [[New South Wales]], [[Australia]]]] A '''pebble''' is a piece of [[clastic rock|rock]] with a [[particle size]] of 4 to 64 millimetres. They are often made of [[flint]]. Pebbles are 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 (geology)|conglomerate]]. Pebble tools are among the earliest known man-made [[Artifact (archaeology)|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 resists wave [[erosion]], and has [[ecological niche]]s which can provide [[habitat]] for animals and plants. [[Category:Sedimentary rocks]]