1.5 metre diameter 'concretion' found at Lyme Regis.

A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity (i.e. the spaces between the sediment grains). Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and cresco meaning 'to grow'. Concretions form within layers of sedimentary strata that have already been deposited. They usually form early in the burial history of the sediment, before the rest of the sediment is hardened into rock. This concretionary cement often makes the concretion harder and more resistant to weathering than the host stratum. Image File history File linksMetadata Download high-resolution version (2560x1920, 2036 KB) Photographer: User:Ballista I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File linksMetadata Download high-resolution version (2560x1920, 2036 KB) Photographer: User:Ballista I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Lyme Regis (IPA: ) is a coastal town in West Dorset, England, situated 25 miles west of Dorchester and 25 miles east of Exeter. ... This article or section does not adequately cite its references or sources. ... Minerals are natural compounds formed through geological processes. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Goldenville Strata exposed at a quarry in Bedford, Canada. ... Weathering is the process of breaking down rocks, soils and their minerals through direct contact with the atmosphere. ... Goldenville Strata exposed at a quarry in Bedford, Canada. ...

Descriptions dating from the 18th century attest to the fact that concretions have long been regarded as fascinating geological curiosities. Because of the variety of unusual shapes, sizes and compositions, concretions have been variously interpreted to be dinosaur eggs, animal and plant fossils (called pseudofossils), extra-terrestrial debris or human artefacts. (17th century - 18th century - 19th century - more centuries) As a means of recording the passage of time, the 18th century refers to the century that lasted from 1701 through 1800. ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... Three small ammonite fossils, each approximately 1. ... A pseudofossil is a fake fossil, or a false fossil. ... I archaeology, an artifact or artefact is any object made or modified by a human culture, and often one later recovered by some archaeological endeavor. ...

Origins

Detailed studies (i.e., Boles et al., 1985; Thyne and Boles, 1989; Scotchman, 1991; Mozley and Burns, 1993; McBride et al., 2003; Chan et al., 2005; Mozley and Davis, 2005) published in peer-reviewed journals, have demonstrated that they form subsequent to burial during diagenesis. They quite often, but not always, form by the precipitation of a considerable amount of cementing material around a nucleus, often organic, such as a leaf, tooth, piece of shell or fossil. For this reason, fossil collectors commonly break open concretions in their search for fossil animal and plant specimens. One of the most unusual concretion nuclei, as documented by Al-Agha et al. (1995), are World War II military shells, bombs, and shrapnel, which are found inside siderite concretions found in an English coastal salt marsh. In geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration (weathering) and metamorphism. ... Three small ammonite fossils, each approximately 1. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... A shell is a projectile, which, as opposed to a bullet, contains an explosive or other filling, though modern usage includes large solid projectiles previously termed shot (AP, APCR, APCNR, APDS, APFSDS and Proof shot). ... The Massive Ordnance Air Blast (MOAB) bomb produced in the United States. ... A sectioned Shrapnel shell displayed at the Canadian War Museum, Ottawa For other uses, see Shrapnel (disambiguation). ... An Atlantic coastal salt marsh in Connecticut. ...

Depending on the specific environmental conditions present at the time of their formation, concretions can be created by either concentric or pervasive growth (Mozley, 1996; Raiswell and Fisher, 2000). In concentric growth, the concretion grows as successive layers of mineral accrete to its surface. This process results in the radius of the concretion growing with time. In case of pervasive growth, cementation of the host sediments, by infilling of its pore space by precipitated minerals, occurs simultaneously throughout the volume of the area, which in time becomes a concretion. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ...

Appearance

Concretions vary in shape, hardness and size, ranging from objects that require a magnifying lens to be clearly visible to huge bodies three meters in diameter and weighing several thousand pounds. The giant, red concretions occurring in Theodore Roosevelt National Park, in North Dakota, are almost 3 m (10 feet) in diameter. Spheroidal concretions, as large as 9 m (30 feet) in diameter, have been found eroding out of the Qasr El Sagha Formation within the Faiyum depression of Egypt. Concretions are usually similar in color to the rock in which they are found. In shape, concretions occur in a wide variety of shapes, including spheres, disks, tubes, and grape-like or soap bubble-like aggregates. Established in 1978, Theodore Roosevelt National Park is a United States National Park comprising three geographically separated areas of badlands in western North Dakota. ... Official language(s) English Capital Bismarck Largest city Fargo Area  Ranked 19th  - Total 70,762 sq mi (183,272 km²)  - Width 210 miles (340 km)  - Length 340 miles (545 km)  - % water 2. ...

Composition

They are commonly composed of a carbonate mineral such as calcite; an amorphous or microcrystalline form of silica such as chert, flint, or jasper; or an iron oxide or hydroxide such as goethite and hematite. They can also be composed of other minerals that include dolomite, ankerite, siderite, pyrite, marcasite, barite and gypsum, to name a few. In organic chemistry, a carbonate is a salt of carbonic acid. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Chert Chert (IPA: ) is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. ... A flint nodule from the Onondaga limestone layer, Buffalo, New York. ... Polished jasper pebble, one inch (2. ... Goethite, named after the German polymath Johann Wolfgang von Goethe, is an iron bearing oxide mineral found in soil and other low temperature environments. ... Hematite (AE) or haematite (BE) is the mineral form of Iron(III) oxide, (Fe2O3), one of several iron oxides. ... Dolomite crystals from Touissite, Morocco Dolomite is the name of both a carbonate rock and a mineral consisting of calcium magnesium carbonate (formula: CaMg(CO3)2) found in crystals. ... Ankerite is a calcium, iron, magnesium, manganese carbonate mineral of the dolomite family with formula: Ca(Fe,Mg,Mn)(CO3)2. ... Siderite is also the name of a type of iron meteorite. ... This article is about the mineral Pyrite or Fools Gold. ... The mineral marcasite, sometimes called white iron pyrite, is iron sulfide (FeS2). ... Baryte with Cerussite from Morocco Baryte with Galena and Hematite from Poland Barite (BaSO4) is a mineral consisting of barium sulfate. ... Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. // Heating gypsum to between 100°C and 150°C (302°F) partially dehydrates the mineral by driving off exactly 75% of the water contained in its chemical structure. ...

Although concretions often consist of single dominate mineral, other minerals can be present in variable amounts depending the specific environmental conditions, which created them. For example, carbonate concretions, which form in response to the reduction of sulfates by bacteria, often contain variable, but typically minor, percentages of pyrite. Other concretions, which formed as a result of microbial sulfate reduction, consist of a mixture of calcite, barite, and pyrite in variable proportions. Sulfate is the IUPAC name for the SO42- ion, consisting of a central sulfur atom single bonded to four tetrahedrally oriented oxygen atoms. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ...

Occurrence

Concretions are found in a wide variety of rocks, and are particularly common in shales, siltstones, and sandstones. They often outwardly resemble fossils or rocks that look as if they do not belong to the stratum in which they were found. Occasionally, concretions contain a fossil, either as its nucleus or as a component that was incorporated during its growth but concretions are not fossils themselves. They appear in nodular patches, concentrated along bedding planes, protruding from weathered cliffsides, randomly distributed over mudhills or perched on soft pedestals. Small hematite concretions (a.k.a. blueberries) have recently been observed on Mars (see Moqui Marbles below). Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Siltstone Siltstone is a geological term for a sedimentary rock whose composition is intermediate in grain size between the coarser sandstone and the finer mudstone. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ...

Types of Concretions

Some of the types and names, which are often found mentioned on the Internet and in popular articles, of concretions are septarian concretions, cannonball concretions, Moqui (Moki) marbles, and pop rocks.

a septarian nodule

Septarian concretions (or septarian nodules) are concretions containing angular cavities or cracks, which are called "septaria". The process or processes, which created the septaria, which characterize septarian concretions, remains an unresolved mystery. A number of mechanisms, i.e. the dehydration of clay-rich, gel-rich, or organic-rich cores; shrinkage of the concretion's center; expansion of gases produced by the decay of organic matter; brittle fracturing of the concentration by either earthquakes or compaction; and others, have been proposed for the formation of septaria. At this time, it is uncertain, which, if any, of these and other proposed mechanisms is responsible for the formation of septaria in septarian concretions (McBride et al. 2003). Septaria usually contain crystals precipitated from circulating solutions, usually of calcite. A well-known and spectacular example of septarian concretions, which are as much as 3 meters (9 feet) in diameter, is the Moeraki Boulders. These concretions are found eroding out of Paleocene mudstone of the Moeraki Formation exposed along the coast near near Moeraki, South Island, New Zealand. They are composed of calcite-cemented mud with septarian veins of calcite and rare late-stage quartz and ferrous dolomite (Boles et al. 1985, Thyne and Boles 1989). Very similar concretions, which are as much as 3 meter (9 feet) in diameter and called "Koutu Boulders", litter the beach between Koutu and Kauwhare points along the south shore of the Hokianga Harbour of Hokianga, North Island, New Zealand. The much smaller septarian concretions found in the Kimmeridge Clay exposed in cliffs along the Wessex Coast of England are more typical examples of septarian concretions (Scotchman 1991). Image File history File linksMetadata Download high-resolution version (1704x2272, 2036 KB) A septarian nodule on display as part of the Pinch Collection at the Canadian Museum of Nature in Ottawa, Ontario. ... Image File history File linksMetadata Download high-resolution version (1704x2272, 2036 KB) A septarian nodule on display as part of the Pinch Collection at the Canadian Museum of Nature in Ottawa, Ontario. ... The Moeraki Boulders are a large number of spherical concretions, found strewn across a beach at Moeraki, a small settlement just south of Hampden on New Zealands Otago coast. ... The Paleocene, early dawn of the recent, is a geologic epoch that lasted from 65. ... Moeraki is a small fishing village located on the east coast of the South Island of New Zealand. ... The South Island The South Island is one of the two major islands of New Zealand, the other being the North Island. ... The Hokianga Harbour, also known as The Hokianga River or more frequently simply as The Hokianga is a long estuarial drowned valley and its surrounding area on the west coast in the north of the North Island of New Zealand. ... North Island The North Island is one of the two main islands of New Zealand, the other being the South Island. ... The Kimmeridge Clay Formation is, arguably, the most economically important unit of rocks in the whole of Europe, being the major source rock for oil fields in the North Sea hydrocarbon province. ... Motto: (French for God and my right) Anthem: God Save the King/Queen Capital London (de facto) Largest city London Official language(s) English (de facto) Unification    - by Athelstan AD 927  Area    - Total 130,395 km² (1st in UK)   50,346 sq mi  Population    - 2006 est. ...

Cannonball concretions are large spherical concretions, which resemble cannonballs. Cannonball concretions, which are found along the Cannonball River within Morton and Sioux Counties, North Dakota, are as large as 3 m (10 feet) in diameter. They were created by early cementation of sand and silt by calcite. Similar cannonball concretions, which are as much as 4 to 6 m (12 to 18 feet) in diameter, are found associated with sandstone outcrops of the Frontier Formation in northeast Utah and central Wyoming. They formed by the early cementation of sand by calcite (McBride et al. 2003). Somewhat weathered and eroded giant cannonball concretions, as large as 6 meters (18 feet) in diameter, occur in abundance at "Rock City" in Ottawa County, Kansas. The Moeraki and Koutu boulders of New Zealand are example of septarian concretions, which are also cannonball concretions. Large spherical rocks, which are found on the shore of Lake Huron near Kettle Point, Ontario, and locally known as "kettles", are typical cannonball concretions. Cannonball concretions have also been reported from Van Mijenfjorden, Spitsbergen; near Haines Junction, Yukon Territory, Canada; and many other places around the world. The Cannonball River The Cannonball River is a tributary of the Missouri River, approximately 135 mi (217 km) long, in southwestern North Dakota in the United States. ... Official language(s) English Capital Bismarck Largest city Fargo Area  Ranked 19th  - Total 70,762 sq mi (183,272 km²)  - Width 210 miles (340 km)  - Length 340 miles (545 km)  - % water 2. ... Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... Official language(s) English Capital Salt Lake City Largest city Salt Lake City Area  Ranked 13th  - Total 84,876 sq mi (219,887 km²)  - Width 270 miles (435 km)  - Length 350 miles (565 km)  - % water 3. ... Official language(s) English Capital Cheyenne Largest city Cheyenne Area  Ranked 10th  - Total 97,818 sq mi (253,348 km²)  - Width 280 miles (450 km)  - Length 360 miles (580 km)  - % water 0. ... Rock City, in Ottawa County, Kansas, is a field nearly 200 spheres of Dakota sandstone found on an otherwise flat prairie. ... Ottawa County (standard abbreviation: OT) is a county located in the state of Kansas. ... Ipperwash Beach, Lake Huron. ... Chippewas of Kettle and Stony Point First Nation, or Kettle Point No. ... Map of Svalbard, showing Spitsbergen in the North. ...

Elongate concretions form parallel to sedimentary strata and have been studied extensively due to the inferred influence of phreatic (saturated) zone groundwater flow direction on the orientation of the axis of elongation (e.g., Johnson, 1989; McBride et al., 1994; Mozley and Goodwin, 1995; Mozley and Davis, 2005). In addition to providing information about the orientation of past fluid flow in the host rock, elongate concretions can provide insight into local permeability trends (i.e., permeability correlation structure; Mozley and Davis, 1996), variation in groundwater velocity (Davis, 1999), and the types of geological features that influence flow.

Moqui Marbles, which are also called "Moqui balls" and "Moki marbles", are iron oxide concretions, which can found eroding in great abundance out of outcrops of the Navajo Sandstone within south-central and southeastern Utah. These concretions range in shape from spheres to discs, buttons, spiked balls, cylindrical forms, and other odd shapes. They range in size of from the size of peas to marbles and, rarely, baseballs. They were created by the precipitation of iron, which was dissolved in groundwater. These concretions are argued to be a terrestrial analogue of the Martian hematite spherules, called "blueberries" (Chan and Parry 2002, Chan et al. 2005). This article belongs in one or more categories. ... This article belongs in one or more categories. ...

Kansas Pop rocks are concretions of either iron sulfide, i.e pyrite and marcasite, or in some cases jarosite, which are found in outcrops of the Smoky Hill Chalk Member of the Niobrara Formation within Grove County, Kansas. They are typically associated with thin layers of altered volcanic ash, called bentonite, which occur within the chalk comprising the Smoky Hill Chalk Member. A few of these concretions enclose, at least in part, large flattened valves of inoceramid bivalves. These concretions range in size from a few millimeters to as much as 0.7 m (2.3 ft) in length and 12 cm (0.4 ft) in thickness. Most of these concretions are oblate spheroids shape. Other "pop rocks" are small polycuboidal pyrite concretions, which are as much as 7 cm (0.23 foot ) in diameter (Hattin 1982). These concretions are called "pop rocks" because they explode if thrown in a fire. Also, when they are either cut or hammered, they produce sparks and a burning sulfur smell. This article is about the mineral Pyrite or Fools Gold. ... The mineral marcasite, sometimes called white iron pyrite, is iron sulfide (FeS2). ... Jarosite is a basic hydrous sulfate of potassium and iron with a chemical formula of KFe3(OH)6(SO4)2. ... Official language(s) none Capital Topeka Largest city Wichita Area  Ranked 15th  - Total 82,277 sq mi (213,096 km²)  - Width 211 miles (340 km)  - Length 417 miles (645 km)  - % water 0. ... Bentonite - USGS Bentonite is an absorbent aluminium phyllosilicate generally impure clay consisting mostly of montmorillonite, (Na,Ca)0. ... The Needles,situated on the Isle Of Wight, are part of the extensive Southern England Chalk Formation. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ...

Iron sulfide concretions, such as the Kansas Pop rocks, consisting of either pyrite and marcasite, are nonmagnetic (Hobbs and Hafner 1999). On the other hand, iron sulfide concretions, which either are composed of or contain either pyrrhotite or symthite, will be magnetic to varying degrees (Hoffmann, 1993). Prolonged heating of either a pyrite or marcasite concretion will convert portions of either mineral into pyrrhotite causing the concretion to become slightly magnetic. Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: Fe(1-x)S (x = 0 to 0. ...

References Cited

• Al-Agha, M.R., S.D. Burley, C.D. Curtis, and J. Esson, 1995, Complex cementation textures and authigenic mineral assemblages in Recent concretions from the Linconshire Wash (east coast, UK) driven by Fe(0) Fe(II) oxidation: Journal of the Geological Society, London, v. 152, pp. 157-171.

• Boles, J.R., C.A. Landis, and P. Dale, 1985, The Moeraki Boulders; anatomy of some septarian concretions:, Journal of Sedimentary Petrology. v. 55, n. 3, pp. 398-406.

• Chan, M.A. and W.T. Parry, 2002, 'Mysteries of Sandstone Colors and Concretions in Colorado Plateau Canyon Country PDF version, 468 KB : Utah Geological Survey Public Information Series. n. 77, pp. 1-19.

• Chan, M.A., B.B. Beitler, W.T. Parry, J. Ormo, and G. Komatsu, 2005. Red Rock and Red Planet Diagenesis: Comparison of Earth and Mars Concretions PDF version, 3.4 MB : GSA Today, v. 15, n. 8, pp. 4-10.

• Davis, J.M., 1999, Oriented carbonate concretions in a paleoaquifer: Insights into geologic controls on fluid flow: Water Resources Research, v. 35, p. 1705-1712.

• Hattin, D.E., 1982, Stratigraphy and depositional environment of the Smoky Hill Chalk Member, Niobrara Chalk (Upper Cretaceous) of the type area, western Kansas: Kansas Geological Survey Bulletin 225:1-108.

• Hobbs, D., and J. Hafnaer, 1999, Magnetism and magneto-structural effects in transition-metal sulphides: Journal of Physics: Condensed Matter, v. 11, pp. 8197-8222.

• Hoffmann, V., H. Stanjek, and E. Murad, 1993, Mineralogical, magnetic and mössbauer data of symthite (Fe9S11) : Studia Geophysica et Geodaetica, v. 37, pp. 366-381.

• Johnson, M.R., 1989, Paleogeographic significance of oriented calcareous concretions in the Triassic Katberg Formation, South Africa: Journal of Sedimentary Petrology, v. 59, p. 1008-1010.

• McBride, E.F., M.D. Picard, and R.L. Folk, 1994, Oriented concretions, Ionian Coast, Italy: evidence of groundwater flow direction: Journal of Sedimentary Research, v. 64, p. 535-540.

• McBride, E.F., M.D. Picard, and K.L. Milliken, 2003, Calcite-Cemented Concretions in Cretaceous Sandstone, Wyoming and Utah, U.S.A.: Journal of Sedimentary Research. v. 73, n. 3, p. 462-483.

• Mozley, P.S., 1996, The internal structure of carbonate concretions: A critical evaluation of the concentric model of concretion growth: Sedimentary Geology: v. 103, p. 85-91.

• Mozley, P.S., and Goodwin, L., 1995, Patterns of cementation along a Cenozoic normal fault: A record of paleoflow orientations: Geology: v. 23, p 539-542.

• Mozley, P.S., and Burns, S.J., 1993, Oxygen and carbon isotopic composition of marine carbonate concretions: an overview: Journal of Sedimentary Petrology, v. 63, p. 73-83.

• Mozley, P.S., and Davis, J.M., 2005, Internal structure and mode of growth of elongate calcite concretions: Evidence for small-scale microbially induced, chemical heterogeneity in groundwater: Geological Society of America Bulletin, v. 117, 1400-1412.

• Raiswell, R., and Q.J. Fisher, 2000, Mudrock-hosted carbonate concretions: a review of growth mechanisms and their influence on chemical and isotopic composition: Journal of Geological Society of London. v. 157, p. 239-251

• Scotchman, I.C., 1991, The geochemistry of concretions from the Kimmeridge Clay Formation of southern and eastern England: Sedimentology. v. 38, pp. 79-106.

• Thyne, G.D., and J.R. Boles, 1989, Isotopic evidence for origin of the Moeraki septarian concretions, New Zealand: Journal of Sedimentary Petrology. v. 59, n. 2, pp. 272-279.

See Also

• Martian spherules
• Moqui Marbles

Spheules still in their originating strata Martian spherules, also known as blueberries, are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars. ... This article belongs in one or more categories. ...

External links

• Biek, B., 2002, Concretions and Nodules in North Dakota North Dakota Geological Survey, Bismark, North Dakota.

• Dietrich, R.V., 2002, Carbonate Concretions--A Bibliography

• Everhart, M., 2004, A Field Guide to Fossils of the Smoky Hill ChalkPart 5: Coprolites, Pearls, Fossilized Wood and other Remains Part of the Oceans of Kansas web site.

• Hansen, M.C., 1994, Ohio Shale Concretions PDF version, 270 KB Ohio Division of Geological Survey GeoFacts n. 4, pp. 1-2.

• Hanson, W.D., and J.M. Howard, 2005, Spherical Boulders in North-Central Arkansas PDF version, 2.8 MB Arkansas Geological Commission Miscellaneous Publication n. 22, pp. 1-23.

• Hokianga Tourism Association, nd, Koutu boulders Really nice pictures of cannonball concretions.

• Katz, B., 1998, Concretions Digital West Media, Inc.

• McCollum, A., nd, Sand Concretions from Imperial Valley, a collection of articles maintained by an American artist.

• Mozley, P.S., Concretions, bombs, and groundwater, on-line version of an overview paper originally published by the New Mexico Bureau of Geology and Mineral Resources.

• United States Geological Survey, nd, cannonball concretion

• University of Utah, 2004, Earth Has 'Blueberries' Like Mars 'Moqui Marbles' Formed in Groundwater in Utah's National Parks press release about iron oxide and Martian concretions