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Pebble
A pebble is a clastic rocks, clast of rock (geology), rock with a grain size, particle size of based on the Particle size (grain size), Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than Granule (geology), granules ( in diameter) and smaller than Cobble (geology), cobbles ( 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. Pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pebble Lane
A pebble is a clast of rock with a particle size of based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules ( in diameter) and smaller than cobbles ( in 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, 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. Pebbles come in various colors and textures and can have streaks, known as veins, of quartz or other minerals. Pebbles are mostly smooth but, dependent on how ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conglomerate (geology)
Conglomerate () is a sedimentary rock made up of rounded gravel-sized pieces of rock surrounded by finer-grained sediments (such as sand, silt, or clay). The larger fragments within conglomerate are called clasts, while the finer sediment surrounding the clasts is called the matrix. The clasts and matrix are typically cemented by calcium carbonate, iron oxide, silica, or hardened clay. Conglomerates form when rounded gravels deposited by water or glaciers become solidified and cemented by pressure over time. They can be found in sedimentary rock sequences of all ages but probably make up less than 1 percent by weight of all sedimentary rocks. They are closely related to sandstones in origin, and exhibit many of the same types of sedimentary structures, such as tabular and trough cross-bedding and graded bedding.Boggs, S. (2006) ''Principles of Sedimentology and Stratigraphy.'', 2nd ed. Prentice Hall, New York. 662 pp. Friedman, G.M. (2003) ''Classification of sediments and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beach Rocks And Pebbles
A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from rock, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc shells or coralline algae. Sediments settle in different densities and structures, depending on the local wave action and weather, creating different textures, colors and gradients or layers of material. Though some beaches form on inland freshwater locations such as lakes and rivers, most beaches are in coastal areas where wave or current action deposits and reworks sediments. Erosion and changing of beach geologies happens through natural processes, like wave action and extreme weather events. Where wind conditions are correct, beaches can be backed by coastal dunes which offer protection and regeneration for the beach. However, these natural forces have become more extreme due to climate change, permanently altering beaches at very rapid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oldowan
The Oldowan (or Mode I) was a widespread stone tool archaeological industry during the early Lower Paleolithic spanning the late Pliocene and the first half of the Early Pleistocene. These early tools were simple, usually made by chipping one, or a few, flakes off a stone using another stone. Oldowan tools were used during over a period spanning from 2.9 million years ago up until at least 1.7 million years ago (Ma), by ancient hominins (early humans) across much of Africa. This technological industry was followed by the more sophisticated Acheulean industry (two sites associated with ''Homo erectus'' at Gona in the Afar Region of Ethiopia dating from 1.5 and 1.26 million years ago have both Oldowan and Acheulean tools). The term ''Oldowan'' is taken from the site of Olduvai Gorge in Tanzania, where the first Oldowan stone tools were discovered by the archaeologist Louis Leakey in the 1930s. However, some contemporary archaeologists and palaeoanthropologists prefer to use th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobble (geology)
A cobble (sometimes a cobblestone) is a clast of rock defined on the Udden–Wentworth scale as having a particle size of , larger than a pebble and smaller than a boulder. Other scales define a cobble's size differently. A rock made predominantly of cobbles is termed a conglomerate. Cobblestone is a building material based on cobbles. Etymology Cobbles, also called cobblestones, derive their name from the word cob, meaning a rounded lump. The term is further related to the German ', meaning ''head''. Chester Wentworth referred to cobbles as ''cobble bowlders'' in his 1922 paper that would become the basis for the Udden–Wentworth scale. Classifications Within the widely used Krumbein phi scale of grain sizes, cobbles are defined as clasts of rock ranging from −6 to −8 φ. This classification corresponds with the Udden–Wentworth size scale which defines cobbles as clasts with diameters from . On this scale, cobbles are larger than pebbles which measure in diame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armor (hydrology)
In hydrology and geography, armor is the association of surface pebbles, rocks or boulders with stream beds or beaches. Most commonly hydrological armor occurs naturally; however, a man-made form is usually called '' riprap'', when shorelines or stream banks are fortified for erosion protection with large boulders or sizable manufactured concrete objects. When armor is associated with beaches in the form of pebbles to medium-sized stones grading from two to 200 millimeters across, the resulting landform A landform is a land feature on the solid surface of the Earth or other planetary body. They may be natural or may be anthropogenic (caused or influenced by human activity). Landforms together make up a given terrain, and their arrangement ... is often termed a '' shingle beach''. Hydrological modeling indicates that stream armor typically persists in a flood stage environment. Hjulstroms diagram Bed armor is most often transported through entrainment, and mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granule (geology)
A granule is a clastic rocks, clast of rock (geology), rock with a particle size of 2 to 4 millimetres based on the Particle size (grain size), Krumbein phi scale of sedimentology. Granules are generally considered to be larger than sand (0.0625 to 2 millimetres diameter) and smaller than pebbles (4 to 64 millimetres diameter). A rock made predominantly of granules is termed a granule Conglomerate (geology), conglomerate.Folk, R.L. (1980) ''The Petrology of Sedimentary Rocks.'' Austin, Texas, Hemphill Publishing Company. 182 pp. See also *Gravel *Particle size (grain size) References Stone (material) Sedimentology Granularity of materials {{Sedimentology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Size (grain Size)
Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which refers to the size of a single crystal inside a particle or grain. A single grain can be composed of several crystals. Granular material can range from very small colloidal particles, through clay, silt, sand, gravel, and cobbles, to boulders. Krumbein phi scale Size ranges define limits of classes that are given names in the Wentworth scale (or Udden–Wentworth scale named after geologists Chester K. Wentworth and Johan A. Udden) used in the United States. The Krumbein ''phi'' (φ) scale, a modification of the Wentworth scale created by W. C. Krumbein in 1934, is a logarithmic scale computed by the equation :\varphi=-\log_2, where :\varphi is the Krumbein phi scale, :D is the diameter of the particle or grain in millimeters (Krumbein a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeolithic
The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehistoric technology. It extends from the earliest known use of stone tools by Hominini, hominins, 3.3 million years ago, to the end of the Pleistocene, 11,650 Before Present#Radiocarbon calibration, cal Before Present, BP. The Paleolithic Age in Europe preceded the Mesolithic Age, although the date of the transition varies geographically by several thousand years. During the Paleolithic Age, hominins grouped together in small societies such as band society, bands and subsisted by gathering plants, fishing, and hunting or scavenging wild animals. The Paleolithic Age is characterized by the use of Knapping, knapped stone tools, although at the time humans also used wood and bone tools. Other organic commodities were adapted for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shingle Beach
A shingle beach, also known as either a cobble beach or gravel beach, is a commonly narrow beach that is composed of coarse, loose, well-rounded, and waterworn gravel, called ''shingle''. The gravel (shingle) typically consists of smooth, spheroidal to flattened, pebbles, cobbles, and sometimes small boulders, generally in the size range. Shingle beaches typically have a steep slope on both their landward and seaward sides. Shingle beaches form in wave-dominated locations where resistant bedrock cliffs provide gravel-sized rock debris. They are also found in high latitudes and temperate shores where the erosion of Quaternary glacial deposits provide gravel-size rock fragments. This term is most widely used in Great Britain.Neuendorf, Klaus K.E. Mehl, James P., Jr. Jackson, Julia A., 2011. ''Glossary of Geology'' (5th Edition). American Geosciences Institute. Narayana, A. C., 2016. ''Coastal landforms''. in Kennish, M.J., ed., pp. 143–157, ''Encyclopedia of Estuaries''. Spr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, transports it to another location where it is deposit (geology), deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by Solvation, dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and Wind wave, waves; glacier, glacial Plucking (glaciation), plucking, Abrasion (geology), abrasion, and scour; areal flooding; Aeolian processes, wind abrasion; groundwater processes; and Mass wastin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
