Sea wave polishing pebbles into rounded corners

Pebbles

A pebble is a clast of rock with a particle size of 4 to 64 millimeters based on the Krumbein phi scale of sedimentology. Clastic rocks are composed of fragments or clasts, of pre-existing rock. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to William Christian Krumbein (1902-1979 was a notable geologist after whom the Krumbein Medal of the International Association for Mathematical Geology (IAMG was named Sedimentology encompasses the study of modern Sediments such as sand, mud (silt and clay and understanding the processes that deposit them It is generally described to be larger than gravel and smaller than cobble. Gravel is rock that is of a specific Particle size range In Geology, gravel is any loose rock that is larger than two millimeters (2mm A rock made predominantly of pebbles is termed a conglomerate. A conglomerate (kɒnˈglɒmərət is a rock consisting of individual stones that have become cemented together Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history. A broader definition of a tool is an entity used to interface between two or more domains that facilitates more effective action of one domain upon the other The term Paleolithic (or Palaeolithic) (from Greek παλαιός palaios, " Old " and λίθος Lithos, "stone" They have been found at Olduvai Gorge (1. The Olduvai Gorge or Oldupai Gorge is commonly referred to as "The Cradle of Mankind 85 million years ago) and at Longuopo in China (1. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National 8 to 1. 5 MYA).

A beach composed chiefly of surface pebbles is commonly termed a shingle beach, which has armoring characteristics with respect to wave erosion; moreover, this type of beach has unusual ecological niches that may provide habitat for a number of rare and endangered species. A shingle beach is a Beach which is armoured with Pebbles or small to medium sized cobbles Armor, in Hydrology and Geography is the association of surface Pebbles rocks or Boulders with Stream beds or Beaches Most Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind A habitat (which is Latin for "it inhabits" is an Ecological or environmental area that is inhabited by a particular Species. A rare species is an Organism which is very uncommon or scarce An endangered species is a population of an organism which is at risk of becoming Extinct because it is either few in numbers or threatened by changing environmental or predation

See also

• Gravel