weathering and decomposition therefore arkose is designated a texturally immature sedimentary rock. Arkose ... monolith Uluru Ayers Rock is composed of late Neoproterozoic Cambrian arkose, deposited in the Amadeus ... rocks Category Sandstone ca Arcosa cs Ark za de Arkose et Arkoos es Arcosa eu Arkosa fr Arkose it Arcosa he ka nl Arkose no Arkose pl Arkoza pt Arcose ro Arcoza sk Ark za sr ... more details
Infobox rockunit name Pebbly Arkose image caption type Geological formation age prilithology otherlithology namedfor namedby region country coordinates unitof subunits underlies overlies thickness extent area map map caption The Pebbly Arkose is a Mesozoic geologic Formation geology formation . Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus . ref name dinosaurdistribution Weishampel, et al. 2004 . Dinosaur distribution. Pp. 517 607. ref See also List of dinosaur bearing rock formations List of stratigraphic units with indeterminate dinosaur fossils Footnotes Portal box Earth sciences Paleontology Dinosaurs Reflist References Weishampel, David B. Dodson, Peter and Osm lska, Halszka eds. The Dinosauria, 2nd, Berkeley University of California Press. 861 pp. ISBN 0 520 24209 2. Category Mesozoic geologic formations geologic formation stub ... more details
Arkose sand in the Llano Uplift personal photo taken on a geology field trip in November 1997. The general environment was that of a braided stream with granite outcrops the picture simply cannot convey the scene s simple beauty. PD self date February 2009 Copy to Wikimedia Commons bot Fbot priority true ... more details
Sparagmite from the Latin sparagma , meaning fragment is an Arkose sandstone or comglomerate so named by Jens Esmark in 1829. ref Landet blir til ISBN 978 82 92344 31 6, p133 ref Deposited in the neoproterozoic to early Cambrian eras, ref Landet blir til ISBN 978 82 92344 31 6, p136 ref the sparagmite nappes were transported up to several hundred kilometers during the Caledonian collision. References refs Category Sandstone ... more details
Pseudomatrix , as defined by Bill Dickinson in 1970, is the term for lithic fragment geology lithic fragments that have been deformed to become part of or exclusively a traditional sandstone matrix geology matrix . This is formed when a lithic rich sandstone is compacted. The compaction is usually more effective on the typically weaker lithic fragments in comparison to the stronger, coarser grained framework grains. References Dickinson, W.R., 1970, Interpreting detrital modes of graywacke and arkose Journal of Sedimentary Petrology, v. 40, p. 695 707. Category Geology ... more details
Grus is an accumulation of angular, coarse grained fragments particles of sand and gravel resulting from the granular disintegration of crystalline rocks most notably granitoid s generally in an arid or semiarid region. ref Bates and Jackson, Dictionary of Geological Terms, 3rd Ed. ref Grus sand, when cement ed into a sandstone , will form an arkose . References reflist Category Geology terminology ... more details
File QFLtriangle.jpg thumb QFL triangle showing schematic plots of common sand compositions A QFL diagram or QFL triangle is a type of Ternary plot ternary diagram that shows compositional data from sandstones and modern sands , point counted using the Gazzi Dickinson Method Gazzi Dickinson method . The abbreviations used are as follows Q quartz F feldspar L lithic fragment geology lithic fragments In general, the most contentious item counted is chert , which is usually counted as a lithic fragment, but is sometimes better suited in the Q pole. When this happens, the pole is renamed Qt instead of Q. The importance of a QFL triangle is mainly demonstrated in tectonic exercises. As first demonstrated in the 1979 paper by William R. Dickinson Bill Dickinson and Chris Suczek, ref Dickinson, W.R., Suczek, C.A., 1979, Plate tectonics and sandstone compositions American Association of Petroleum Geologist, 63, 2164 2182 ref the composition and provenance of a sandstone is directly related to its tectonic environment of formation. Craton sands are clustered near the Q pole. As sandstones, these are known as quartz arenite s. Transitional continental sands are along the QF line. As sandstones, these are known as arkose s. Basement Tectonic uplift uplift sands are near the F pole. This includes thick skinned tectonics. As sandstones, these are known as arkose s. Recycled orogen sands plot near the Q pole, but with significant F and L components. This includes thin skinned tectonics common in subduction back arc thrusting. As sandstones, these are known as lithic sandstone s. Volcanic arc Arc sands plot along the F and L line, with sometimes significant Q components. Clustering near the F pole indicates a dissected arc, and clustering near the L pole indicates an undissected, or new arc. As sandstones, these are known as arkose s and or lithic sandstone s. References Reflist Category Petrology petrology stub ... more details
In sedimentology , a prism is a long, narrow, wedge shaped sedimentary body. These types of sediments are typically formed during orogeny orogenic deformation for example, the arkose detrital sedimentary rock found in fault trough s. ref name AP cite book last1 Scientific American title Scientific American, Supplement Volume 16 volume 16 work Munn and Co date 1883 url http books.google.com books?id 0 48AQAAIAAJ&pg PA6513&lpg PA6513&dq arkose prism&source bl&ots ohGKRwAAQ &sig 35ibHRvVCw24GvbAEE8Gvynj9rU&hl en&ei cfDgTuC7EYyFtged5sCvDg&sa X&oi book result&ct result&resnum 1&ved 0CCgQ6AEwAA v onepage&q arkose 20prism&f false accessdate 2011 12 08 ref File Aigue marine sur quartz et tourmaline noire Pakistan .jpg thumb Hexagonal aquamarine prism with stubby quartz prisms In mineralogy , prismatic is also type of mineral habit appearance of a crystal . Prismatic minerals have crystals that show a uniform Cross section geometry cross section . Prismatic crystals typically have 3, 4, 6, 8 or 12 faces which are parallel to a Optic axis of a crystal crystallographic axis . ref name Klein Klein, Cornelis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley 1985, 20th ed. p. 44 and 359 ISBN 0 471 80580 7 ref The apatite group of minerals commonly exhibit elongated hexagonal prisms. ref name Klein Accretionary prism main Accretionary wedge An accretionary prism or accretionary wedge is formed from sediments that are Accretion geology accreted onto the non Subduction subducting tectonic plate at a Convergent boundary convergent plate boundary . Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing Slab geology slab of oceanic crust but in some cases includes the erosional products of volcanic island arc s formed on the overriding plate. Crystal habit main Crystal habit Crystal habit is an overall description of the visible external shape of a mineral. This description can apply to an individual crystal or an assembly of ... more details
fragments indicate that the rock is an arkose, a subarkose or a lithic arkose, one must then normalize ..., the rock is either a plagioclase arkose, a plagioclase subarkose or a lithic plagioclase arkose ... a distinction between the feldspars, the name stays as arkose, subarkose or lithic arkose, respectively ... more details
G nis greenschist G nis sericite schist Puy de Cornut arkose G nis porphyroid G nis greenschist The G nis ... Silurian age rare finds of Ordovician acritarch s have been made . Puy de Cornut arkose Below the G nis sericite schist follows the Puy de Cornut arkose . The arkose is strongly silica silicified and forms ... in Brittany is also considered. Therefore an Ordovician age of the arkose is most likely. G nis ... more details
The Newark Group , also known as the Newark Supergroup , is an assemblage of Late Triassic and Early Jurassic sedimentary rocks which outcrop intermittently along the United States East Coast of the United States East Coast the exposures extend from Massachusetts to North Carolina , with more still in Nova Scotia . It is named for the city of Newark, New Jersey . Characteristics Image UpperTriassicYorkCountyPA.jpg thumb New Oxford Conglomerate Upper Triassic, York County, Pennsylvania a unit within the Newark Group. The Newark Group consists largely of poorly sorted nonmarine sediments typical rocks are breccia , Conglomerate geology conglomerate , arkose arkose sandstone , siltstone , and shale . ref James Monroe and Reed Wicander, The Changing Earth Exploring Geology and Evolution , 2nd ed. Belmont West Publishing Company, 1997 , p. 602. ref ref Carl Schuchert and Carl Dunbar, Outlines of Historical Geology , 4th ed. New York John Wiley & Sons, Inc., 1947 , p. 108. ref Most of the strata are red beds that feature ripple marks , mud cracks, and even rain drop prints dinosaur footprints are common, though actual body fossil s are very rare. ref Schuchert and Dunbar, p. 108. ref Some of the strata are detailed to the level of varve s, with indications of Milankovitch cycle s. ref Michael J. Benton, The Penguin Historical Atlas of the Dinosaurs , London Penguin Books Ltd., 1996 , 88 9. ref In preserved lake sediments, Semionotus fossils are especially common. ref Ibid. ref The Newark sediments are extremely thick up to 6 kilometers they were deposited in a series of half graben s that were themselves fault geology faulted into block mountains. ref Monroe and Wicander, p. 605 ref The beds dip to the east, while the faults dip westward. ref Ibid. ref The beds are intruded by numerous Dike geology dikes and sill geology sill s, indicative of considerable igneous rock igneous activity a superb example is the New Jersey Palisades sill. ref Ibid. ref Formation The Newark Gr ... more details
Image WheelerPeak.JPG thumb Quartz arenite makes up the Prospect Mountain Quartzite on top of Wheeler Peak Nevada A quartz arenite or quartzarenite is a sandstone composed of greater than 90 detrital quartz ref Blatt, Harvey and Robert J. Tracy, Petrology Igneous, Sedimentary, and Metamorphic , Freeman 2nd ed., 1996, p. 518 ISBN 0 7167 2438 3 ref , with limited amounts of other framework grains feldspar , lithic fragments , etc. and matrix geology matrix . It can have higher than average amounts of resistant grains, like chert and minerals in the ZTR index . The term quartz arenite is derived from the main component quartz and arenite , a Latin term for a rock with sand sized grains. In some literature, these can be called orthoquartzite s, a confusing term which usually refers to the metamorphic rock quartzite , though most metamorphic quartzites are diagentically fused from quartz arenites. The term quartzose sandstone can also be used for a quartz arenite. Quartz arenites are the most maturity sedimentology mature sedimentary rock s possible, and are often referred to as ultra or super mature, and are usually cemented by silica. They often exhibit both textural and compositional maturity. The two primary sedimentary depositional environment s that produce quartz arenites are beach es upper shoreface and aeolian processes ref Prothero, D. R. and Schwab, F., 1996, Sedimentary Geology, pg. 96 98, ISBN 0 7167 2726 9 ref , due to their high residence time, high transport distance, and or high energy of the environment. Most of the time, these sediments are reworked over and over, even being eroded out of a lithified rock and becoming a brand new sediment and rock. This is known as a multicycle sand. See also Lithic sandstone Arkose References Reflist DEFAULTSORT Quartz Arenite Category Sedimentary rocks Category Sandstone petrology stub eu Kuartzoarenita ... more details
Arenite Latin Arena , sand is a sedimentary rock sedimentary clastic rock with sand Particle size grain size grain size between 0.0625 mm 0.00246 in and 2 mm 0.08 in and contain less than 15 Matrix geology matrix . ref http www.britannica.com eb article 9009339 arenite Britannica definition of arenite . Accessed on January 1, 2008 ref The related adjective is arenaceous . The equivalent Modern Greek Greek derived term is psammite , though this is more commonly used for metamorphic rock metamorphosed sediments. Since it refers to grain size rather than chemical composition, the term is used for example in the classification of clastic carbonatic limestones, as the Particle size grain size granulometrically equivalent term sandstone is not appropriate for limestone. Other arenites include sandstone s, arkose s, greensand s, and greywacke s. Arenites mainly form by erosion of other rocks or turbidite turbiditic re deposition of sands. Some arenites contain a varying amount of calcium carbonate carbonatic components and thus belong to the rock category of carbonatic sandstones or silicate silicatic limestone s. Arenites often appear as massive or bedded medium grained rocks with a middling to wide spaced preferred foliation and often develop a pronounced cleavage geology cleavage . Pettijohn ref Francis J. Pettijohn Pettijohn F. J. 1975 , Sedimentary Rocks , Harper & Row, ISBN 0 96 045191 2 ref gives the following descriptive terms based on grain size, avoiding the use of terms such as clay or argillaceous which carry an implication of chemical composition class wikitable Descriptive size terms Texture Common Greek Latin Coarse gravel ly psephite psephitic rudite rudaceous Medium sand y psammite psammitic arenite arenaceous Fine clay ey pelite pelitic lutite lutaceous References reflist Category Sedimentary rocks Category Sandstone de Arenit fr Ar nite vi Arenit ... more details
Image Papago Buttes 3.jpg thumb 350px right Hole in the Rock, west front side shown Hole in the Rock is a natural geology geological formation in Papago Park , a municipal park of Phoenix, Arizona Phoenix and Tempe, Arizona . Description Hole in the Rock is a series of openings tafoni erosion eroded in a small hill composed of bare red arkose arkosic conglomerate sandstone . The sandstone was first formed some 6 15 million years ago, theorized to have been the accumulation of materials sliding off a much higher mountain, which, made of different materials, has long since eroded away, leaving what looks like petrified mud cakes. The tafoni are thought to have been eroded by water. An open, shelter like chamber in the face of the formation communicates with the rear of the formation via a hole eroded completely through the rock. Another substantial opening exists in the ceiling of the chamber. There is evidence that the Hohokam , early inhabitants of the region, used and recorded the position of sunlight shining through the latter opening to mark the seasons&mdash notably the equinox es and the solstice s, which were marked by carving a slick area metate in the rock. Other positions were marked with boulder s. The formation is a popular attraction in the park. The openings and main chamber, near the summit, are easily accessible via a smoothly ascending path that passes behind the hill. It is also possible to climb the face of the hill to reach the chamber, although this is dangerous for the inexperienced. The chamber provides a good view of the city of Phoenix, Arizona Phoenix west of the park. A nearly constant wind blows through the openings in the rock. External links Portal Arizona http phoenix.gov PARKS hikpafac.html Papago Park Facts provided by the City of Phoenix http www.gemland.com holeinrock.htm Hole in the Rock provided by Gemland PhxPoP Coord 33 27 30 N 111 56 39 W display title DEFAULTSORT Hole In The Rock Papago Park Category Geography of Phoenix, Ariz ... more details
File Lithic arenite.jpg thumb left Photomicrograph of a lithic arenite sandstone from the Wolfville Formation Jurassic . Top image is in plane polarized light PPL bottom image is in cross polarized light XPL . Blue epoxy fills pore spaces. File LvMS Lvm.jpg thumb Photomicrograph of a volcanic sand grain upper picture is plane polarized light, bottom picture is cross polarized light, scale box at left center is 0.25 millimeter. This type of grain is a main component of a lithic sandstone. Lithic sandstones , or lithic arenites , or litharenites , are sandstone s with a significant 5 component of lithic fragments , though quartz and feldspar are usually present as well, along with some matrix geology clayey matrix . Lithic sandstones can have a speckled salt and pepper or gray color, and are usually associated with one specific type of lithic fragment i.e., igneous , sedimentary , or Metamorphic rock metamorphic . ref Prothero, D. R. and Schwab, F., 1996, Sedimentary Geology, pg. 100, ISBN 0 7167 2726 9 ref Tectonically, lithic sandstones often form in a wide variety sedimentary depositional environment s including fluvial , river delta deltaic , and alluvial sediments associated with active margin s. This tectonic setting provides the source of the lithic fragments, either through arc volcanism , Thrust tectonics Thin skinned deformation thin skinned faulting , Thrust tectonics Collisional zones continental collisions , unroofing , and subduction roll back . See also Arkose Quartz arenite References references Category Sedimentary rocks Category Sandstone petrology stub ... more details
The Oronto group is a thick Group geology group of arkose sandstone and shale located beneath the Bayfield Group in northern Wisconsin , ref name B48 Bulletin, p. 48. ref and believed to extend into Minnesota . ref name B49 Because it is almost entirely red in color and highly tilted, it is considered separate from the Bayfield Group. ref name B48 The Oronto group is divided into the Copper Harbor Conglomerate, Freda Sandstone, and Nonesuch Shale . ref Scott W. Imbus and others, Organic geochemistry and sedimentology of middle Proterozoic Nonesuch Formation hydrocarbon source rock assessment of a lacustrine rift deposit, in Lacustrine Basin Exploration , Tulsa, Okla. American Association of Petroleum Geologists, p.197 208 ref As the group is devoid of fossils, its age is difficult to ascertain, ref name B100 Bulletin, p. 100. ref though it may be of Keweenawan Age about 1100 Mya unit Mya . ref name B105 Bulletin, p. 105. ref The group is composed of Conglomerate geology conglomerate , sandstone and shale. It is typically red, with bands, streaks, and spots of greenish white no more than a few inches thick. ref name B49 Bulletin, p. 49. ref The total thickness of the group is unknown, but may be as much as convert 21000 ft m abbr on deep. ref name B50 Bulletin, p. 50. ref The Oronto group has a higher proportion of undecomposed minerals, feldspar s, mica s, ferromagnesian compounds, magnetite and calcium carbonate than the Bayfield Group. ref name B49 Notes Reflist References cite book title Bulletin, Issue 25 year 1912 publisher Wisconsin Geological and Natural History Survey url http books.google.com books?id wJTPAAAAMAAJ Category Geology of Wisconsin Category Sedimentary rocks ... more details
Image Achille Delesse.jpg thumb Achille Delesse Achille Ernest Oscar Joseph Delesse 3 February 1817 24 March 1881 was a France French geologist and mineralogist . He was born at Metz . At the age of twenty he entered the Ecole Polytechnique , and subsequently passed through the cole nationale sup rieure des mines de Paris Ecole des Mines . In 1845, he was appointed to the chair of mineralogy and geology at Besan on in 1850, to the chair of geology at the University of Paris Sorbonne in Paris, France Paris and in 1864, professor of agriculture at the Ecole des Mines. In 1878, he became inspector general of mines. In early years as ing nieur des mines he investigated and described various new mineral s he proceeded afterward to the study of Rock geology rock s, devising new methods for their determination, and giving particular descriptions of melaphyre , arkose , Porphyry geology porphyry , syenite , and others. The igneous rock s of the Vosges , and those of the Alps , Corsica , etc., and the subject of metamorphism occupied his attention. He also prepared in 1858 geological and hydrological maps of Paris, with reference to the underground water, similar maps of the d partement in France d partement s of the Seine and Seine et Marne , and an agronomic map of the Seine et Marne 1880 , in which he showed the relation that exists between the physical and chemical characters of the soil and the geological structure. His annual Revue des progr s de g ologie , undertaken with the assistance 1860 1865 of Auguste Laugel and afterwards 1865 1878 of Albert Auguste Cochon de Lapparent Albert de Lapparent , was carried on from 1860 to 1880. His observations on the lithology of the deposits accumulated beneath the sea were of special interest and importance. His separate publications were Recherches sur l origine des roches Paris, 1865 tude sur le m tamorphisme des roches 1869 , Lithologie des mers de France et des mers principales du globe 2 vols. and atlas, 1871 . He died in ... more details
Lithic fragments , or lithics, are pieces of other Rock geology rocks that have been eroded down to sand size and now are sand grains in a sedimentary rock . They were first described and named in their modern definitions by William R. Dickinson Bill Dickinson in 1970. ref Dickinson, W.R., 1970, Interpreting detrital modes of graywacke and arkose Journal of Sedimentary Petrology, v. 40, p. 695 707. ref Lithic fragments can be derived from sedimentary, Igneous rock igneous or metamorphic rocks . A lithic fragment is defined using the Gazzi Dickinson Method Gazzi Dickinson point counting method and being in the Particle size grain size sand size fraction. Sand grains in sedimentary rocks that are fragments of larger rocks that are not identified using the Gazzi Dickinson method are usually called rock fragment s instead of lithic fragments. Sandstone s rich in lithic fragments are called lithic sandstone s. Types of lithic fragments Igneous Lv These can include granular Rhyolite rhyolitic , microlitic Andesite andesitic , lathwork Basalt basaltic , and vitric Volcanic glass glassy . These correlations between composition and volcanic lithic fragment type are approximate, at best. ref Affolter, M.D. and Hendrix, M. S., 2004, Correlations between volcanic lithic fragments and volcanic rock, Geological Society of America Abstracts with Programs, Vol. 36, No. 5, p. 370 ref By definition, intrusive igneous rock fragments can not be considered lithic fragments. Sedimentary Ls These can include shale and siltstone fragments, and at times chert . Metamorphic Lm These can include fine grained schist and phyllite fragments, among others. gallery Image LvMS Lvg.jpg Granular volcanic lithic fragment, scale in millimeters Top picture in plane polarized light, bottom picture in cross polarized light. Image LvMS Lvm.jpg Microlitic volcanic lithic fragment, scale in millimeters. Top picture in plane polarized light, bottom picture in cross polarized light. Image LvMS Lvl&Lvsm.jpg Lat ... more details
and blue grey arkose sandstone beige righthand only conglomerate. Red arrows indicate extent of range. South Sugarloaf Mountain, arkose, is located just below the lower arrow. The Pocumtuck Range is composed of Sugarloaf arkose , a weather resistant sedimentary rock capped in places by a thin ridge of volcanic trap rock . The arkose is most apparent on Sugarloaf Mountain and the western cliff of Pocumtuck ... border. The Pocumtuck Range forms the bottom and middle layers of a geologic layercake. The arkose is the oldest ... more details
Infobox rockunit name New Red Sandstone image caption Type Geological formation prilithology Sandstone otherlithology Arkose , Conglomerate geology conglomerate namedfor namedby region Global country United Kingdom coordinates unitof subunits thickness extent area age Permian to Triassic The New Red Sandstone is a chiefly United Kingdom British geology geological term for the beds of red sandstone and associated rocks laid down throughout the Permian 280 million years ago to the beginning of the Triassic 240 million years ago that underlie the Jurassic Lias the term distinguishes it from the Old Red Sandstone which is largely Devonian in age. Its upper layers consist of mudstones, but most of the formation consists of reddish sandstones, interbedded with rare evaporite minerals such as halite and gypsum these indicate deposition within a hot and arid palaeo environment e.g. a desert or sabkha . Central UK locations The New Red Sandstone covers much of central England , where it generally forms a low lying plain. Thick layers up to 1100 m thick are present in the Fault geology faulted Cheshire Basin which also extends beneath north Shropshire . There are numerous escarpment s forming small prominent hills within this area. The sandstone also underlies parts of Lancashire and Cumbria , and east of the Pennines it extends through Nottinghamshire and central Yorkshire . Smaller outcrops occur in other parts of Britain such as the Red Cliffs of Dawlish and East Devon . Lithology In terms of its lithology , the New Red Sandstone comprises true sandstones, mudrocks and evaporite stratum strata . The sandstone member is monomineralic, consisting only of quartz grains negligible amounts of other minerals may be present , and they are cemented together with the ferric iron oxide haematite Fe sub 2 sub O sub 3 sub . The presence of this particular iron oxide is evidence for a Terrestrial ecoregion terrestrial Sedimentary depositional environment environment of d ... more details
Infobox rockunit name Fountain Formation image Roxborough.jpg caption Red rocks typical of The Fountain Formation seen at Roxborough State Park near Littleton, Colorado type sedimentary age Late Pennsylvanian prilithology sandstone , Conglomerate geology conglomerate otherlithology limestone , shale namedfor Fountain Creek namedby C. W. Cross, 1894 region Denver Basin country coordinates unitof subunits underlies Lyons Formation overlies Gleneyrie Formation thickness 0 4500 ft ref Frederickson, E.A., De Lay, M., and Saylor, W.W., 1956, Ralston formation of Canon City embayment, Colorado American Association of Petroleum Geologists Bulletin, v. 40, no. 9, p. 2120 2148. ref extent Colorado, Wyoming area map map caption The Fountain Formation is a Pennsylvanian bedrock unit consisting primarily of conglomerate geology conglomerate , sandstone , or arkose , in the states of Colorado and Wyoming in the USA , along the east side of the Front Range of the Rocky Mountains , and along the west edge of the Denver Basin . Origin of name The Fountain Formation was named by geologist W. C. Cross in 1894 for exposures along Fountain Creek in El Paso County, Colorado El Paso County ref Cross, C.W., 1894, Description of the Pikes Peak sheet Colorado U.S. Geological Survey Geologic Atlas of the United States, Pikes Peak folio, no. 7, 5 p. ref . Stratigraphy Image Fountain fm unconf redrocks.jpg thumb left Fountain Formation unconformably overlying Precambrian rocks at the parking lot of Red Rocks Park The Fountain unconformity unconformably overlies Precambrian granite and gneiss. Outcrops of the formation typically dip steeply to the east. Depositional environment The formation was formed by the erosion of the Ancestral Rocky Mountains , and deposition by fluvial processes as alluvial fan s. The characteristic predominant red color and the composition of the Fountain reflect that of the granite s and gneiss es from which it was eroded. Notable Exposures Image Fountain fm garden of ... more details
Infobox rockunit name Patuxent Formation image caption type Sedimentary age Early Cretaceous prilithology sand, clay otherlithology namedfor Patuxent River namedby W. B. Clark, 1897 ref name Clark1897 Clark, W.B., 1897, Outline of present knowledge of the physical features of Maryland Maryland Geological Survey Volume Series, v. 1, pt. 3, p. 172 188. ref region Atlantic coastal plain country U.S.A. coordinates unitof Potomac Group subunits underlies Arundel Formation overlies Basement geology basement rocks thickness extent Maryland, Washington D. C., Delaware, Virginia area map map caption The Patuxent Formation is a Cretaceous geologic Formation geology formation of the Atlantic coastal plain . Description The Patuxent formation was first described by W. B. Clark in 1897 ref name Clark1897 . The formation is primarily unconsolidated sand and clay . The sand often contains Kaolinite kaolinized feldspar , making it an arkose . Clay lumps are common, and sand beds gradually transition to clay. Sandy beds may be Cross bedding crossbedded , which is evidence of shallow water origin. The Patuxent is the basal unit of the Coastal Plain sedimentary formations and unconformity unconformably overlies the crystalline Basement geology basement rocks . This underlying unconformity is the subsurface equivalent of the Atlantic Seaboard Fall line . Fossils Propanoplosaurus , a nodosaurid known from a single natural cast and mold of a hatchling, was found recovered from rocks belonging to the Patuxent Formation in Maryland. ref Ray Stanford, David B. Weishampel and Valerie B. Deleon 2011 The First Hatchling Dinosaur Reported from the Eastern United States Propanoplosaurus marylandicus Dinosauria Ankylosauria from the Early Cretaceous of Maryland, U.S.A. Journal of Paleontology 85 5 916 924. http www.bioone.org doi abs 10.1666 10 113.1 ref Fossil Stegosauria stegosaur tracks have been reported from the formation. ref name dinosaurdistribution Weishampel, et al. 2004 . Dinosaur dist ... more details
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