Editing Pebble (section)

{{Short description|Small rock fragment}}
{{About||the smartwatch|Pebble (watch)|other}}
{{More citations needed|date=December 2013}}
[[File:Pebble Dash (15366562092).jpg|thumb|upright=1.35|Close view of pebbles{{Vague|date=February 2023|reason=How big are these pebbles?}}]]

A '''pebble''' is a [[clastic rocks|clast]] of [[rock (geology)|rock]] with a [[grain size|particle size]] of {{cvt|4-64|mm|in}} based on the [[Particle size (grain size)|Udden-Wentworth scale]] of [[sedimentology]]. Pebbles are generally considered larger than [[Granule (geology)|granules]] ({{cvt|2-4|mm|in}} in diameter) and smaller than [[Cobble (geology)|cobbles]] ({{cvt|64-256|mm|in}} in diameter). A rock made predominantly of pebbles is termed a [[conglomerate (geology)|conglomerate]].  [[oldowan|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 [[armor (hydrology)|armoring characteristics]] with respect to wave [[erosion]], as well as ecological niches that provide [[habitat]] for animals and plants.

Inshore banks of shingle (large quantities of pebbles) exist in some locations, such as the entrance to the [[River Ore]], England, where the moving banks of shingle give notable navigational challenges.<ref>{{cite web|url=http://www.visitmyharbour.com/harbours/east-coast/ore-alde-rivers/|title=Ore and Alde, Rivers - East Coast: pilotage, charts, photos and marine business listings|website=www.visitmyharbour.com}}</ref>

Pebbles come in various colors and textures and can have streaks, known as [[Vein (geology)|vein]]s, of [[quartz]] or other [[mineral]]s. Pebbles are mostly smooth but, dependent on how frequently they come in contact with the sea, they can have marks of contact with other rocks or other pebbles. Pebbles left above the [[tide|high water mark]] may have growths of organisms such as [[lichen]] on them, signifying the lack of contact with [[seawater]].