The Jurassic period was a geologic period and system that spanned 56 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era known as the Age of Reptiles; the start of the period was marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian-Toarcian extinction in the Early Jurassic, the Tithonian event at the end; the Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations; the Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified. By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north, Gondwana to the south; this created more coastlines and shifted the continental climate from dry to humid, many of the arid deserts of the Triassic were replaced by lush rainforests.
On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to an aquatic mode of life; the oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates. The chronostratigraphic term "Jurassic" is directly linked to the Jura Mountains, a mountain range following the course of the France–Switzerland border. During a tour of the region in 1795, Alexander von Humboldt recognized the limestone dominated mountain range of the Jura Mountains as a separate formation that had not been included in the established stratigraphic system defined by Abraham Gottlob Werner, he named it "Jura-Kalkstein" in 1799.
The name "Jura" is derived from the Celtic root *jor via Gaulish *iuris "wooded mountain", borrowed into Latin as a place name, evolved into Juria and Jura. The Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations known as Lias and Malm in Europe; the separation of the term Jurassic into three sections originated with Leopold von Buch. The faunal stages from youngest to oldest are: During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Jurassic North Atlantic Ocean was narrow, while the South Atlantic did not open until the following Cretaceous period, when Gondwana itself rifted apart. The Tethys Sea closed, the Neotethys basin appeared. Climates were warm, with no evidence of a glacier having appeared; as in the Triassic, there was no land over either pole, no extensive ice caps existed.
The Jurassic geological record is good in western Europe, where extensive marine sequences indicate a time when much of that future landmass was submerged under shallow tropical seas. In contrast, the North American Jurassic record is the poorest of the Mesozoic, with few outcrops at the surface. Though the epicontinental Sundance Sea left marine deposits in parts of the northern plains of the United States and Canada during the late Jurassic, most exposed sediments from this period are continental, such as the alluvial deposits of the Morrison Formation; the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus common, along with calcitic ooids, calcitic cements, invertebrate faunas with dominantly calcitic skeletons; the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, South America, Japan and the United Kingdom.
In Africa, Early Jurassic strata are distributed in a similar fashion to Late Triassic beds, with more common outcrops in the south and less common fossil beds which are predominated by tracks to the north. As the Jurassic proceeded and more iconic groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are neither well studied in Africa. Late Jurassic strata are poorly represented apart from the spectacular Tendaguru fauna in Tanzania; the Late Jurassic life of Tendaguru is similar to that found in western North America's Morrison Formation. During the Jurassic period, the primary vertebrates living in the sea were marine reptiles; the latter include ichthyosaurs, which were at the peak of their diversity, plesiosaurs and marine crocodiles of the families Teleosauridae and Metriorhynchidae. Numerous turtles could be found in rivers. In the invertebrate world, several new groups appeared, including rudists (a reef-formi
Santa Barbara County, California
Santa Barbara County, California the County of Santa Barbara, is a county located in the southern region of the U. S. state of California. As of the 2010 census, the population was 423,895; the county seat is Santa Barbara, the largest city is Santa Maria. Santa Barbara County comprises CA Metropolitan Statistical Area. Most of the county is part of the California Central Coast. Mainstays of the county's economy include engineering, resource extraction, winemaking and education; the software development and tourism industries are important employers in the southern part of the county. Southern Santa Barbara County is sometimes considered the northern cultural boundary of Southern California; the Santa Barbara County area, including the Northern Channel Islands, was first settled by Native Americans at least 13,000 years ago. Evidence for a Paleoindian presence has been found in the form of a fluted Clovis-like point found in the 1980s along the western Santa Barbara Coast, as well as the remains of Arlington Springs Man found on Santa Rosa Island in the 1960s.
For thousands of years, the area was home to the Chumash tribe of Native Americans, complex hunter-gatherers who lived along the coast and in interior valleys leaving rock art in many locations, including Painted Cave. Europeans first contacted the Chumash in AD 1542, when three Spanish ships under the command of Juan Rodríguez Cabrillo explored the area; the Santa Barbara Channel received its name from Spanish explorer Sebastián Vizcaíno when he sailed along the California coast in 1602. Spanish ships associated with the Manila Galleon trade made emergency stops along the coast during the next 167 years, but no permanent settlements were established; the first land expedition to explore California, led by Gaspar de Portolà explored the coastal area in 1769, on its way to Monterey Bay. The party traveled the same route on the return to San Diego in January 1770; that same year, a second expedition to Monterey again passed through the area. The DeAnza expeditions of 1774-76 followed Portola's trail.
The Presidio of Santa Barbara was established in 1782, followed by Mission Santa Barbara in 1786 – both in what is now the city of Santa Barbara. The presidio and mission kept Vizcaino's denomination, as did the city and county – a common practice which has preserved the names of many of the 21 California Missions. European contacts had devastating effects on the Chumash people, including a series of disease epidemics that drastically reduced Chumash population; the Chumash survived and thousands of Chumash descendants still live in the Santa Barbara area or surrounding counties. A tribal homeland was established in the Santa Ynez Reservation. Following the Mexican secularization of the missions in the 1830s, the mission pasture lands were broken up into large ranchos and granted to prominent local citizens who lived in the area. 604 of these land grants were confirmed by the state of California, with 36 in Santa Barbara County. Santa Barbara County was one of the 27 original counties of California, formed in 1850 at the time of statehood.
The county's territory was divided to create Ventura County in 1873. According to the U. S. Census Bureau, the county has a total area of 3,789 square miles, of which 2,735 square miles is land and 1,054 square miles is water. Four of the Channel Islands – San Miguel Island, Santa Cruz Island, Santa Rosa Island and Santa Barbara Island – are in Santa Barbara County, they form the largest part of the Channel Islands National Park. Santa Barbara County has a mountainous interior abutting several coastal plains on the west and south coasts of the county; the largest concentration of population is on the southern coastal plain, referred to as the "south coast" – meaning the part of the county south of the Santa Ynez Mountains. This region includes the cities of Santa Barbara and Carpinteria, as well as the unincorporated areas of Hope Ranch, Mission Canyon and Isla Vista, along with stretches of unincorporated area such as Noleta/Nanta Barbara. North of the Santa Ynez range in the Santa Ynez Valley are the towns of Santa Ynez, Buellton, Lompoc.
North of the Santa Ynez Valley are the cities of Santa Maria and Guadalupe, the unincorporated towns of Orcutt, Los Alamos, Casmalia and Sisquoc. In the extreme northeastern portion of the county are the small cities of New Cuyama and Ventucopa; as of January 1, 2006, Santa Maria has become the largest city in Santa Barbara County. The principal mountain ranges of the county are the Santa Ynez Mountains in the south, the San Rafael Mountains and Sierra Madre Mountains in the interior and northeast. Most of the mountainous area is within the Los Padres National Forest, includes two wilderness areas: the San Rafael Wilderness and the Dick Smith Wilderness; the highest elevation in the county is 6820 feet at Big Pine Mountain in the San Rafaels. North of the mountains is the arid and sparsely populated Cuyama Valley, portions of which are in San Luis Obispo and Ventura Counties. Oil production and agriculture dominate the land use in the owned parts of the Cuyama Valley.
Sandstone is a clastic sedimentary rock composed of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds form visible cliffs and other topographic features, certain colors of sandstone have been identified with certain regions. Rock formations that are composed of sandstone allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be changed into quartzite through metamorphism related to tectonic compression within orogenic belts.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals; the cements binding these grains together are calcite and silica. Grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are called argillaceous sediments; the formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Sedimentation occurs by the sand settling out from suspension. Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains; the most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried.
Colors will be tan or yellow. A predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe and Mongolia; the regularity of the latter favours use as a source for masonry, either as a primary building material or as a facing stone, over other forms of construction. The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings: Terrestrial environmentsRivers Alluvial fans Glacial outwash Lakes Deserts Marine environmentsDeltas Beach and shoreface sands Tidal flats Offshore bars and sand waves Storm deposits Turbidites Framework grains are sand-sized detrital fragments that make up the bulk of a sandstone.
These grains can be classified into several different categories based on their mineral composition: Quartz framework grains are the dominant minerals in most clastic sedimentary rocks. These physical properties allow the quartz grains to survive multiple recycling events, while allowing the grains to display some degree of rounding. Quartz grains evolve from plutonic rock, which are felsic in origin and from older sandstones that have been recycled. Feldspathic framework grains are the second most abundant mineral in sandstones. Feldspar can be divided into two smaller subdivisions: plagioclase feldspars; the different types of feldspar can be distinguished under a petrographic microscope. Below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the chemical composition of the mineral can range from KAlSi3O8 to NaAlSi3O8, this represents a complete solid solution. Plagioclase feldspar is a complex group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8.
Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, called lithic fragments or clasts. Lithic fragments can be any fine-grained or coarse-grained igneous, metamorphic, or sedimentary rock, although the most common lithic fragments found in sedimentary rocks are clasts of volcanic rocks. Accessory minerals are all other mineral grains in a sandstone. Common accessory minerals include micas, olivine and corundum. Many of these accessory grains are more dense than the silicates that
San Andreas Fault
The San Andreas Fault is a continental transform fault that extends 1,200 kilometers through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, its motion is right-lateral strike-slip; the fault divides into three segments, each with different characteristics and a different degree of earthquake risk. The slip rate along the fault ranges from 20 to 35 mm /yr; the fault was identified in 1895 by Professor Andrew Lawson of UC Berkeley, who discovered the northern zone. It is described as having been named after San Andreas Lake, a small body of water, formed in a valley between the two plates. However, according to some of his reports from 1895 and 1908, Lawson named it after the surrounding San Andreas Valley. Following the 1906 San Francisco earthquake, Lawson concluded that the fault extended all the way into southern California. In 1953, geologist Thomas Dibblee concluded that hundreds of miles of lateral movement could occur along the fault. A project called the San Andreas Fault Observatory at Depth near Parkfield, Monterey County, was drilled through the fault during 2004 – 2007 to collect material and make physical and chemical observations to better understand fault behavior.
The northern segment of the fault runs from Hollister, through the Santa Cruz Mountains, epicenter of the 1989 Loma Prieta earthquake up the San Francisco Peninsula, where it was first identified by Professor Lawson in 1895 offshore at Daly City near Mussel Rock. This is the approximate location of the epicenter of the 1906 San Francisco earthquake; the fault returns onshore at Bolinas Lagoon just north of Stinson Beach in Marin County. It returns underwater through the linear trough of Tomales Bay which separates the Point Reyes Peninsula from the mainland, runs just east of Bodega Head through Bodega Bay and back underwater, returning onshore at Fort Ross. From Fort Ross, the northern segment continues overland, forming in part a linear valley through which the Gualala River flows, it goes back offshore at Point Arena. After that, it runs underwater along the coast until it nears Cape Mendocino, where it begins to bend to the west, terminating at the Mendocino Triple Junction; the central segment of the San Andreas Fault runs in a northwestern direction from Parkfield to Hollister.
While the southern section of the fault and the parts through Parkfield experience earthquakes, the rest of the central section of the fault exhibits a phenomenon called aseismic creep, where the fault slips continuously without causing earthquakes. The southern segment begins near California. Box Canyon, near the Salton Sea, contains upturned strata associated with that section of the fault; the fault runs along the southern base of the San Bernardino Mountains, crosses through the Cajon Pass and continues northwest along the northern base of the San Gabriel Mountains. These mountains are a result of movement along the San Andreas Fault and are called the Transverse Range. In Palmdale, a portion of the fault is examined at a roadcut for the Antelope Valley Freeway; the fault continues northwest alongside the Elizabeth Lake Road to the town of Elizabeth Lake. As it passes the towns of Gorman, Tejon Pass and Frazier Park, the fault begins to bend northward, forming the "Big Bend"; this restraining bend is thought to be where the fault locks up in Southern California, with an earthquake-recurrence interval of 140–160 years.
Northwest of Frazier Park, the fault runs through the Carrizo Plain, a long, treeless plain where much of the fault is plainly visible. The Elkhorn Scarp defines the fault trace along much of its length within the plain; the southern segment, which stretches from Parkfield in Monterey County all the way to the Salton Sea, is capable of an 8.1-magnitude earthquake. At its closest, this fault passes about 35 miles to the northeast of Los Angeles; such a large earthquake on this southern segment would kill thousands of people in Los Angeles, San Bernardino and surrounding areas, cause hundreds of billions of dollars in damage. The Pacific Plate, to the west of the fault, is moving in a northwest direction while the North American Plate to the east is moving toward the southwest, but southeast under the influence of plate tectonics; the rate of slippage averages about 33 to 37 millimeters a year across California. The southwestward motion of the North American Plate towards the Pacific is creating compressional forces along the eastern side of the fault.
The effect is expressed as the Coast Ranges. The northwest movement of the Pacific Plate is creating significant compressional forces which are pronounced where the North American Plate has forced the San Andreas to jog westward; this has led to the formation of the Transverse Ranges in Southern California, to a lesser but still significant extent, the Santa Cruz Mountains. Studies of the relative motions of the Pacific and North American plates have shown that only about 75 percent of the motion can be accounted for in the movements of the San Andreas and its various branch faults; the rest of the motion has been found in an area east of the Sierra Nevada mountains called the Walker Lane or Eastern California Shear Zone. The reason for this is not clear. Several hypotheses have been offered and research is ongoing. One hypothesis – which gained interest following the Landers earthquake in 1992 – suggests the plate boundary may be shifting eastward aw
Douglas County, Oregon
Douglas County is a county in the U. S. state of Oregon. As of the 2010 census, the population was 107,667; the county seat is Roseburg. It is named after an American politician who supported Oregon statehood. Douglas County comprises OR Micropolitan Statistical Area; the area was inhabited by the Umpqua Indians, who speak a language in the Athabaskan language family. Following the Rogue River Indian War in 1856, most of the remaining natives were moved by the government to the Grand Ronde Indian Reservation. However, seven families of Umpqua hid in eluding capture for many decades, they are now federally recognized as the Cow Creek Band of Umpqua Tribe of Indians. The tribe manages a small reservation in Canyonville and has a Casino/Hotel named Seven Feathers to represent the seven families who refused forced removal to the Grand Ronde Reservation. Douglas County was created on January 7, 1852, from the portion of Umpqua County which lay east of the Coast Range summit. In 1856 the Camas Valley was annexed to Douglas County from Coos County.
In 1862, the rest of Umpqua county was absorbed into Douglas County, some say due to the loss of population following the end of the early gold boom, while others attribute the absorption to politics. Further boundary adjustments were made with Jackson and Lane Counties in 1915. In 2017, after the defeat of a referendum, all public libraries in Douglas County were closed. According to the U. S. Census Bureau, the county has a total area of 5,134 square miles, of which 5,036 square miles is land and 98 square miles is water, it is the fifth-largest county in Oregon by area. A portion of the Umpqua National Forest is in Douglas County. Douglas County is one of two Oregon counties that extend from the Pacific Ocean to the Cascade Range. Crater Lake National Park Rogue River-Siskiyou National Forest Siuslaw National Forest Umpqua National Forest Willamette National Forest Lane County Klamath County Jackson County Josephine County Curry County Coos County As of the census of 2000, there were 100,399 people, 39,821 households, 28,233 families residing in the county.
The population density was 20 people per square mile. There were 43,284 housing units at an average density of 9 per square mile; the racial makeup of the county was 93.86% White, 0.18% Black or African American, 1.52% Native American, 0.63% Asian, 0.09% Pacific Islander, 1.02% from other races, 2.70% from two or more races. 3.27% of the population were Hispanic or Latino of any race. 18.4 % were of 13.2 % American, 12.6 % English and 10.2 % Irish ancestry. 96.5% spoke English and 2.2% Spanish as their first language. There were 39,821 households out of which 29.10% had children under the age of 18 living with them, 57.2% were married couples living together, 9.6% had a female householder with no husband present, 29.1% were non-families. 23.9% of all households were made up of individuals and 11% had someone living alone, 65 years of age or older. The average household size was 2.48 and the average family size was 2.9. In the county, the population was spread out with 24% under the age of 18, 7.5% from 18 to 24, 24.2% from 25 to 44, 26.4% from 45 to 64, 17.8% who were 65 years of age or older.
The median age was 41 years. For every 100 females there were 96.8 males. For every 100 females age 18 and over, there were 94.2 males. The median income for a household in the county was $33,223, the median income for a family was $39,364. Males had a median income of $32,512 versus $22,349 for females; the per capita income for the county was $16,581. About 9.6% of families and 13.1% of the population were below the poverty line, including 16.6% of those under age 18 and 9.2% of those age 65 or over. As of the 2010 United States Census, there were 107,667 people, 44,581 households, 29,839 families residing in the county; the population density was 21.4 inhabitants per square mile. There were 48,915 housing units at an average density of 9.7 per square mile. The racial makeup of the county was 92.4% white, 1.8% American Indian, 1.0% Asian, 0.3% black or African American, 0.1% Pacific islander, 1.2% from other races, 3.2% from two or more races. Those of Hispanic or Latino origin made up 4.7% of the population.
In terms of ancestry, 25.6% were German, 16.7% were Irish, 15.8% were English, 5.7% were American. Of the 44,581 households, 26.4% had children under the age of 18 living with them, 51.2% were married couples living together, 10.8% had a female householder with no husband present, 33.1% were non-families, 26.6% of all households were made up of individuals. The average household size was 2.38 and the average family size was 2.82. The median age was 46.1 years. The median income for a household in the county was $39,711 and the median income for a family was $48,729. Males had a median income of $39,308 versus $28,176 for females; the per capita income for the county was $21,342. About 10.6% of families and 15.6% of the population were below the poverty line, including 24.1% of those under age 18 and 9.0% of those age 65 or over. In contrast to the Willamette Valley, Douglas County is powerfully conservative and Republican, being akin to Josephine County to the south, or to Eastern Oregon. No Democratic presidential nominee has carried Douglas County since Lyndon Johnson’s landslide win in 1964: indeed the last Democrat to crack forty percent of the county’s vote was Michael Dukakis in 1988 during an election influenced by a major drought.
The county, like all of Western Oregon north of the Rogue Valley leaned strongly
Shale is a fine-grained, clastic sedimentary rock composed of mud, a mix of flakes of clay minerals and tiny fragments of other minerals quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility, it is the most common sedimentary rock. Shale exhibits varying degrees of fissility, breaking into thin layers splintery and parallel to the otherwise indistinguishable bedding plane because of the parallel orientation of clay mineral flakes. Non-fissile rocks of similar composition but made of particles smaller than 0.06 mm are described as mudstones or claystones. Rocks with similar particle sizes but with less clay and therefore grittier are siltstones. Shales are composed of clay minerals and quartz grain, are grey. Addition of variable amounts of minor constituents alters the color of the rock. Black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment.
Black shale can be referred to as black metal. Red and green colors are indicative of ferric oxide, iron hydroxide, or micaceous minerals. Clays are the major constituent of other mudrocks; the clay minerals represented are kaolinite and illite. Clay minerals of Late Tertiary mudstones are expandable smectites whereas in older rocks in mid- to early Paleozoic shales illites predominate; the transformation of smectite to illite produces silica, calcium, magnesium and water. These released elements form authigenic quartz, calcite, ankerite and albite, all trace to minor minerals found in shales and other mudrocks. Shales and mudrocks contain 95 percent of the organic matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale. Black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron and sulfur. Pyrite and amorphous iron sulfide along with carbon produce the black coloration; the process in the rock cycle which forms shale is called compaction.
The fine particles that compose shale can remain suspended in water long after the larger particles of sand have deposited. Shales are deposited in slow moving water and are found in lakes and lagoonal deposits, in river deltas, on floodplains and offshore from beach sands, they can be deposited in sedimentary basins and on the continental shelf, in deep, quiet water.'Black shales' are dark, as a result of being rich in unoxidized carbon. Common in some Paleozoic and Mesozoic strata, black shales were deposited in anoxic, reducing environments, such as in stagnant water columns; some black shales contain abundant heavy metals such as molybdenum, uranium and zinc. The enriched values are of controversial origin, having been alternatively attributed to input from hydrothermal fluids during or after sedimentation or to slow accumulation from sea water over long periods of sedimentation. Fossils, animal tracks/burrows and raindrop impact craters are sometimes preserved on shale bedding surfaces.
Shales may contain concretions consisting of pyrite, apatite, or various carbonate minerals. Shales that are subject to heat and pressure of metamorphism alter into a hard, metamorphic rock known as slate. With continued increase in metamorphic grade the sequence is phyllite schist and gneiss. Before the mid-19th century, the terms slate and schist were not distinguished. In the context of underground coal mining, shale was referred to as slate well into the 20th century. Bakken Formation Barnett Shale Bearpaw Formation Burgess Shale Marcellus Formation Mazon Creek fossil beds Oil shale – Organic-rich fine-grained sedimentary rock containing kerogen Shale gas Shale gas in the United States Wheeler Shale Wianamatta Shale Media related to Shale at Wikimedia Commons