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
A waterfall is an area where water flows over a vertical drop or a series of steep drops in the course of a stream or river. Waterfalls occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls are formed in the upper course of a river in steep mountains; because of their landscape position, many waterfalls occur over bedrock fed by little contributing area, so may be ephemeral and flow only during rainstorms or significant snowmelt. The further downstream, the more perennial a waterfall can be. Waterfalls can have a wide range of depths; when the river courses over resistant bedrock, erosion happens and is dominated by impacts of water-borne sediment on the rock, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it may pluck material from the riverbed, if the bed is fractured or otherwise more erodible. Hydraulic jets and hydraulic jumps at the toe of a falls can generate large forces to erode the bed when forces are amplified by water-borne sediment.
Horseshoe-shaped falls focus the erosion to a central point enhancing riverbed change below a waterfalls. A process known as "potholing" involves local erosion of a deep hole in bedrock due to turbulent whirlpools spinning stones around on the bed, drilling it out. Sand and stones carried by the watercourse therefore increase erosion capacity; this causes the waterfall to recede upstream. Over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, it will carve deeper into the ridge above it; the rate of retreat for a waterfall can be as high as one-and-a-half metres per year. The rock stratum just below the more resistant shelf will be of a softer type, meaning that undercutting due to splashback will occur here to form a shallow cave-like formation known as a rock shelter under and behind the waterfall; the outcropping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are broken down into smaller boulders by attrition as they collide with each other, they erode the base of the waterfall by abrasion, creating a deep plunge pool in the gorge downstream.
Streams can become wider and shallower just above waterfalls due to flowing over the rock shelf, there is a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom. However, a study of waterfalls systematics reported that waterfalls can be wider or narrower above or below a falls, so anything is possible given the right geological and hydrological setting. Waterfalls form in a rocky area due to erosion. After a long period of being formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall; as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by earthquakes or landslides or volcanoes can cause a differential in land heights which interfere with the natural course of a water flow, result in waterfalls. A river sometimes flows over a large step in the rocks. Waterfalls can occur along the edge of a glacial trough, where a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted.
The large waterfalls in Yosemite Valley are examples of this phenomenon, referred to as a hanging valley. Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other. Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall using a logarithmic scale. Class 10 waterfalls include Paulo Afonso Falls and Khone Falls. Classes of other well-known waterfalls include Kaieteur Falls. Alexander von Humboldt "Father of Modern Geography" Humboldt was marking waterfalls on maps for river navigation purposes. Oscar von Engeln Published "Geomorphology: systematic and regional", this book had a whole chapter devoted to waterfalls, is one of the earliest examples of published works on waterfalls. R. W. Young Wrote "Waterfalls: form and process" this work made waterfalls a much more serious topic for research for modern Geoscientists. Ledge waterfall: Water descends vertically over a vertical cliff, maintaining partial contact with the bedrock.
Block/Sheet: Water descends from a wide stream or river. Classical: Ledge waterfalls where fall height is nearly equal to stream width, forming a vertical square shape. Curtain: Ledge waterfalls which descend over a height larger than the width of falling water stream. Plunge: Fast-moving water descends vertically, losing complete contact with the bedrock surface; the contact is lost due to horizontal velocity of the water before it falls. It always starts from a narrow stream. Punchbowl: Water descends in a constricted form and spreads out in a wider pool. Horsetail: Descending water maintains contact with bedrock most of the time. Slide: Water glides down maintaining continuous contact. Ribbon: Water descends over a long narrow strip. Chute: A large quantity of water forced through a narrow, vertical passage. Fan: Water spreads horizontally as
Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, the processes by which they change over time. Geology can include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology overlaps all other earth sciences, including hydrology and the atmospheric sciences, so is treated as one major aspect of integrated earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, the processes that have shaped that structure, it provides tools to determine the relative and absolute ages of rocks found in a given location, to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, the Earth's past climates. Geologists use a wide variety of methods to understand the Earth's structure and evolution, including field work, rock description, geophysical techniques, chemical analysis, physical experiments, numerical modelling.
In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, providing insights into past climate change. Geology is a major academic discipline, it plays an important role in geotechnical engineering; the majority of geological data comes from research on solid Earth materials. These fall into one of two categories: rock and unlithified material; the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three major types of rock: igneous and metamorphic; the rock cycle illustrates the relationships among them. When a rock solidifies or crystallizes from melt, it is an igneous rock; this rock can be weathered and eroded redeposited and lithified into a sedimentary rock. It can be turned into a metamorphic rock by heat and pressure that change its mineral content, resulting in a characteristic fabric.
All three types may melt again, when this happens, new magma is formed, from which an igneous rock may once more solidify. To study all three types of rock, geologists evaluate the minerals; each mineral has distinct physical properties, there are many tests to determine each of them. The specimens can be tested for: Luster: Measurement of the amount of light reflected from the surface. Luster is broken into nonmetallic. Color: Minerals are grouped by their color. Diagnostic but impurities can change a mineral’s color. Streak: Performed by scratching the sample on a porcelain plate; the color of the streak can help name the mineral. Hardness: The resistance of a mineral to scratch. Breakage pattern: A mineral can either show fracture or cleavage, the former being breakage of uneven surfaces and the latter a breakage along spaced parallel planes. Specific gravity: the weight of a specific volume of a mineral. Effervescence: Involves dripping hydrochloric acid on the mineral to test for fizzing. Magnetism: Involves using a magnet to test for magnetism.
Taste: Minerals can have a distinctive taste, like halite. Smell: Minerals can have a distinctive odor. For example, sulfur smells like rotten eggs. Geologists study unlithified materials, which come from more recent deposits; these materials are superficial deposits. This study is known as Quaternary geology, after the Quaternary period of geologic history. However, unlithified material does not only include sediments. Magmas and lavas are the original unlithified source of all igneous rocks; the active flow of molten rock is studied in volcanology, igneous petrology aims to determine the history of igneous rocks from their final crystallization to their original molten source. In the 1960s, it was discovered that the Earth's lithosphere, which includes the crust and rigid uppermost portion of the upper mantle, is separated into tectonic plates that move across the plastically deforming, upper mantle, called the asthenosphere; this theory is supported by several types of observations, including seafloor spreading and the global distribution of mountain terrain and seismicity.
There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle. Thus, oceanic plates and the adjoining mantle convection currents always move in the same direction – because the oceanic lithosphere is the rigid upper thermal boundary layer of the convecting mantle; this coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics. The development of plate tectonics has provided a physical basis for many observations of the solid Earth. Long linear regions of geologic features are explained as plate boundaries. For example: Mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, are seen as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes are theorized as convergent boundaries, where one plate subducts, or moves, under another. Transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes.
Plate tectonics has provided a mechan
An oak is a tree or shrub in the genus Quercus of the beech family, Fagaceae. There are 600 extant species of oaks; the common name "oak" appears in the names of species in related genera, notably Lithocarpus, as well as in those of unrelated species such as Grevillea robusta and the Casuarinaceae. The genus Quercus is native to the Northern Hemisphere, includes deciduous and evergreen species extending from cool temperate to tropical latitudes in the Americas, Asia and North Africa. North America contains the largest number of oak species, with 90 occurring in the United States, while Mexico has 160 species of which 109 are endemic; the second greatest center of oak diversity is China, which contains 100 species. Oaks have spirally arranged leaves, with lobate margins in many species. Many deciduous species are marcescent. In spring, a single oak tree produces small female flowers; the fruit is a nut called an oak nut borne in a cup-like structure known as a cupule. The acorns and leaves contain tannic acid, which helps to guard from insects.
The live oaks are distinguished for being evergreen, but are not a distinct group and instead are dispersed across the genus. The oak tree is a flowering plant. Oaks may be divided into two genera and a number of sections: The genus Quercus is divided into the following sections: Sect. Quercus, the white oaks of Europe and North America. Styles are short; the leaves lack a bristle on their lobe tips, which are rounded. The type species is Quercus robur. Sect. Mesobalanus, Hungarian oak and its relatives of Europe and Asia. Styles long; the section Mesobalanus is related to section Quercus and sometimes included in it. Sect. Cerris, the Turkey oak and its relatives of Europe and Asia. Styles long; the inside of the acorn's shell is hairless. Its leaves have sharp lobe tips, with bristles at the lobe tip. Sect. Protobalanus, the canyon live oak and its relatives, in southwest United States and northwest Mexico. Styles short, acorns mature in 18 months and taste bitter; the inside of the acorn shell appears woolly.
Leaves have sharp lobe tips, with bristles at the lobe tip. Sect. Lobatae, the red oaks of North America, Central America and northern South America. Styles long; the inside of the acorn shell appears woolly. The actual nut is encased in a thin, papery skin. Leaves have sharp lobe tips, with spiny bristles at the lobe; the ring-cupped oaks of eastern and southeastern Asia. Evergreen trees growing 10–40 m tall, they are distinct from subgenus Quercus in that they have acorns with distinctive cups bearing concrescent rings of scales. IUCN, ITIS, Encyclopedia of Life and Flora of China treats Cyclobalanopsis as a distinct genus, but some taxonomists consider it a subgenus of Quercus, it contains about 150 species. Species of Cyclobalanopsis are common in the evergreen subtropical laurel forests which extend from southern Japan, southern Korea, Taiwan across southern China and northern Indochina to the eastern Himalayas, in association with trees of genus Castanopsis and the laurel family. Interspecific hybridization is quite common among oaks but between species within the same section only and most common in the white oak group.
Inter-section hybrids, except between species of sections Mesobalanus, are unknown. Recent systematic studies appear to confirm a high tendency of Quercus species to hybridize because of a combination of factors. White oaks are unable to discriminate against pollination by other species in the same section; because they are wind pollinated and they have weak internal barriers to hybridization, hybridization produces functional seeds and fertile hybrid offspring. Ecological stresses near habitat margins, can cause a breakdown of mate recognition as well as a reduction of male function in one parent species. Frequent hybridization among oaks has consequences for oak populations around the world. Frequent hybridization and high levels of introgression have caused different species in the same populations to share up to 50% of their genetic information. Having high rates of hybridization and introgression produces genetic data that does not differentiate between two morphologically distinct species, but instead differentiates populations.
Numerous hypotheses have been proposed to explain how oak species are able to remain morphologically and ecologically distinct with such high levels of gene flow, but the phenomenon is still a mystery to botanists. The Fagaceae, or beech family, to which the oaks belong, is a slow evolving clade compared to other angiosperms, the patterns of hybridization and introgression in Quercus pose a gre
Oak Ridge National Laboratory
Oak Ridge National Laboratory is an American multiprogram science and technology national laboratory sponsored by the U. S. Department of Energy and administered and operated by UT–Battelle as a federally funded research and development center under a contract with the DOE. ORNL is the largest science and energy national laboratory in the Department of Energy system by size and by annual budget. ORNL is located in Oak Ridge, near Knoxville. ORNL's scientific programs focus on materials, neutron science, high-performance computing, systems biology and national security. ORNL partners with the state of Tennessee and industries to solve challenges in energy, advanced materials, manufacturing and physics; the laboratory is home to several of the world's top supercomputers including the world's most powerful supercomputer ranked by the TOP500, is a leading neutron science and nuclear energy research facility that includes the Spallation Neutron Source and High Flux Isotope Reactor. ORNL hosts the Center for Nanophase Materials Sciences, the BioEnergy Science Center, the Consortium for Advanced Simulation of Light-Water Reactors.
Oak Ridge National Laboratory is managed by UT–Battelle, a limited liability partnership between the University of Tennessee and the Battelle Memorial Institute, formed in 2000 for that purpose. The annual budget is US$1.65 billion, 80% of, from the Department of Energy. As of 2012 there are 4,400 staff working at ORNL, 1,600 of whom are directly conducting research, an additional 3,000 guest researchers annually. There are five campuses on the Department of Energy's Oak Ridge reservation; the total area of the reservation 150 square kilometres of which the lab takes up 18 square kilometres. The town of Oak Ridge was established by the Army Corps of Engineers as part of the Clinton Engineer Works in 1942 on isolated farm land as part of the Manhattan Project. During the war, advanced research for the government was managed at the site by the University of Chicago's Metallurgical Laboratory. In 1943, construction of the "Clinton Laboratories" was completed renamed to "Oak Ridge National Laboratory".
The site was chosen for the X-10 Graphite Reactor, used to show that plutonium can be created from enriched uranium. Enrico Fermi and his colleagues developed the world's second self-sustaining nuclear reactor after Fermi's previous experiment, the Chicago Pile-1; the X-10 was the first reactor designed for continuous operation. After the end of World War II the demand for weapons-grade plutonium fell and the reactor and the laboratory's 1000 employees were no longer involved in nuclear weapons. Instead, it was used for scientific research. In 1946 the first medical isotopes were produced in the X-10 reactor, by 1950 20,000 samples had been shipped to various hospitals; as the demand for military science had fallen the future of the lab was uncertain. Management of the lab was contracted by the US government to Monsanto; the University of Chicago re-assumed responsibility, until in December 1947, when Union Carbide and Carbon Co. which operated two other facilities at Oak Ridge, took control of the laboratory.
Alvin Weinberg was named Director of Research, ORNL, in 1955 Director of the Laboratory. In 1950 the Oak Ridge School of Reactor Technology was established with two courses in reactor operation and safety. Much of the research performed at ORNL in the 1950s was relating to nuclear reactors as a form of energy production, both for propulsion and electricity. More reactors were built in the 1950s than in the rest of the ORNL's history combined. Another project was the world's first light water reactor. With its principles of neutron moderation and fuel cooling by ordinary water, it is the direct ancestor of most modern nuclear power stations; the US Military funded much of its development, for nuclear-powered submarines and ships of the US Navy. The US Army contracted portable nuclear reactors in 1953 for heat and electricity generation in remote military bases; the reactors were designed at ORNL, produced by American Locomotive Company and used in Greenland, the Panama Canal Zone and Antarctica.
The United States Air Force contributed funding to three reactors, the lab's first computers, its first particle accelerators. ORNL designed and tested a nuclear-powered aircraft in 1954 as a proof-of-concept for a proposed USAF fleet of long-range bombers, although it never flew; the provision of radionuclides by X-10 for medicine grew in the 1950s with more isotopes available. ORNL was the only Western source of californium-252. ORNL scientists lowered the immune systems of mice and performed the world's first successful bone marrow transplant. In the early 1960s there was a large push at ORNL to develop nuclear-powered desalination plants, where deserts met the sea, to provide water; the project, called Water for Peace, was backed by John F. Kennedy and Lyndon B. Johnson, presented at a 1964 United Nations conference, but increases in the cost of construction and falling public confidence in nuclear power caused the plan to fail; the Health Physics Research Reactor built in 1962 was used for radiation exposure experiments leading to more accurate dosage limits and dosimeters, improved radiation shielding
The Appalachian Plateau is a series of rugged dissected plateaus located on the western side of the Appalachian Mountains. The Appalachian Mountains are a mountain range that run down the entire east coast of the United States; the Appalachian Plateau is the northwestern part of the Appalachian Mountains, stretching from New York to Alabama. The plateau is a second level United States physiographic region, covering parts of the states of New York, Ohio, West Virginia, Kentucky, Tennessee and Georgia; the formation of the plateau began during the Paleozoic Era. Regional uplift during this time caused the area to rise altogether without changing the topography of the land; the eastern side of the plateau appears as a mountain range. This false appearance is due to a steep slope on the eastern side known as the Allegheny Front; the eastern edge is the highest part of the Appalachian Plateau. In Pennsylvania, the altitude ranges from 1,750 to 3,000 feet and continues to rise toward West Virginia, where the elevation is around 4,800 feet.
From West Virginia to Tennessee, the elevation lowers to 3,000 feet and continues slanting downward to 1,000 feet in Alabama. On the western side of the plateau, the elevation is 900 feet in Ohio, increasing to about 2,000 feet in Kentucky. From Kentucky the elevation drops down to 500 feet in northwestern Alabama; the plateau has a slight slant towards the northwest, making it higher on the eastern side. A large portion of the plateau is a coalfield, formed 320 million years ago during the Pennsylvanian Age; the plateau was subjected to glaciation during the Pleistocene ice age. As a result, the topography of this section of the plateau is flat in comparison to the rest of the physiographic province; this portion of the plateau is marked with evidence of a glaciated past including bogs and small hills of sand and gravel. The topography of the rest of the plateau was created from stream erosion; the result is a rugged landscape, unlike many other plateaus, that includes many narrow stream valleys surrounded by steep ridges.
The region in Kentucky is known as the Eastern Kentucky Coalfield. It covers around 30 % of Kentucky's land. Major sections include the Allegheny Plateau, the Cumberland Plateau and the Cumberland Mountains, with the highest peaks located in the Cumberland Mountains. A physiographic region is a large portion of land, grouped together by several factors; each region has similar geology and groups of plants and animals. There are eight physiographic regions in the United States; each region is divided into provinces, there are 25 provinces in the United States. Each region is divided into sections, creating 85 different physio-graphic sections in the United States; the Appalachian Plateau is a province of the physiographic region of the Appalachian Highlands. The Appalachian Plateau province is divided into seven physio-graphic sections: Mohawk, Southern New York, Allegheny Mountains, Cumberland Plateau, the Cumberland Mountains; each section is classified under the Appalachian Plateau province because of its similarities in geologic makeup and wildlife.
The Appalachian Plateau falls under the classification of Appalachian Highlands because of those similar characteristics. The rock underlying the Appalachian Plateau consists of a base of Precambrian rock, overlain by sedimentary rock from the Paleozoic Era. On top of the basement is a thick layer 20,000 feet, of a mixture of Cambrian and Middle Silurian rock; this rock consists of shale and sandstone. Above this layer is the Upper Silurian evaporate basin, or basin of chemically formed sedimentary rocks; the Plateau fold belt consists of structurally complex Paleozoic strata which were thrust faulted over the younger evaporates. When the Appalachian mountains were formed, the plateau was lifted. Ridges and valleys all die down underneath the plateau. There are multiple valleys throughout the region which consist of exposed areas of limestone and shale. Archaeologists have evidence that Native Americans lived in the Appalachian region more than twelve thousand years ago. Human artifacts were collected near the Meadowcroft Rockshelter in southern Pennsylvania that were at least sixteen thousand years old.
Because the early Native Americans were hunter-gatherers living off the land, they left little material traces of their lives behind them. This is. Much like many historic Native American tribes, the early Appalachian inhabitants survived as nomads, following their food on a seasonal basis. Around this period, North America was still recuperating from its last glacial period, the climate was much different than now; the climate and habitat more resembled a tundra, with lower temperatures, numerous conifer trees, large mammals, such as mammoths and saber-toothed tigers. The climate began to warm up again, the large mammals started to disappear, the vegetation seen more today began to flourish; these climatic changes made life more sustainable for the Native Americans. They continued to invent new weapons and made advancements in agriculture until the Europeans arrived in North America. Europeans settled in North America beginning in the seventeenth century. In 1749, Jacob Martin and Steven Sewell were the first Europeans known to settle the Appalachian Plateau in what is now Pocahontas County in West Virginia.
European colonization and competition with the Native Americans resulted in high mortality due to new diseases, as well as more deaths and social disr
Hickory is a type of tree, comprising the genus Carya. The genus includes 17 to 19 species. Five or six species are native to China and India, as many as 12 are native to the United States, four are found in Mexico, two to four are from Canada. A number of hickory species are used for products like edible nuts or wood. Hickories are deciduous trees with large nuts. Hickory flowers are small, yellow-green catkins produced in spring, they are self-incompatible. The fruit is a globose or oval nut, 2–5 cm long and 1.5–3 cm diameter, enclosed in a four-valved husk, which splits open at maturity. The nut shell is thick and bony in most species, thin in a few, notably the pecan. Beaked hickory is a species classified as Carya sinensis, but now adjudged in the monotypic genus Annamocarya. In the APG system, genus Carya has been moved to the order Fagales. AsiaCarya sect. Sinocarya – Asian hickories Carya dabieshanensis M. C. Liu – Dabie Shan hickory Carya cathayensis Sarg. – Chinese hickory Carya hunanensis W.
C. Cheng & R. H. Chang – Hunan hickory Carya kweichowensis Kuang & A. M. Lu – Guizhou hickory Carya poilanei Leroy - Poilane's hickory Carya tonkinensis Lecomte – Vietnamese hickoryNorth AmericaCarya sect. Carya – typical hickories Carya floridana Sarg. – scrub hickory Carya glabra Sweet – pignut hickory, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory, broom hickory Carya laciniosa K. Koch – shellbark hickory, shagbark hickory, bigleaf shagbark hickory, big shellbark, bottom shellbark, thick shellbark, western shellbark Carya myristiciformis Nutt. – nutmeg hickory, swamp hickory, bitter water hickory Carya ovalis Sarg. – red hickory, spicebark hickory, sweet pignut hickory Carya ovata K. Koch – shagbark hickory Carya ovata var. ovata – northern shagbark hickory Carya ovata var. australis – Southern shagbark hickory, Carolina hickory Carya pallida Engl. & Graebn. – sand hickory Carya texana Buckley – black hickory Carya tomentosa Nutt. – mockernut hickory †Carya washingtonensis - Manchester extinct Miocene Carya sect.
Apocarya – pecans Carya aquatica Nutt. – bitter pecan or water hickory Carya cordiformis K. Koch – bitternut hickory Carya illinoinensis K. Koch – pecan Carya palmeri W. E. Manning – Mexican hickory Hickory is used as a food plant by the larvae of some Lepidoptera species; these include: Luna moth Brown-tail Coleophora case-bearers, C. laticornella and C. ostryae Regal moths, whose caterpillars are known as hickory horn-devils Walnut sphinx The bride Hickory tussock moth The hickory leaf stem gall phylloxera uses the hickory tree as a food source. Phylloxeridae are related to aphids and have a complex life cycle. Eggs hatch in early spring and the galls form around the developing insects. Phylloxera galls may damage weakened or stressed hickories, but are harmless. Deformed leaves and twigs can rain down from the tree in the spring as squirrels break off infected tissue and eat the galls for the protein content or because the galls are fleshy and tasty to the squirrels; the pecan gall curculio is a true weevil species found feeding on galls of the hickory leaf stem gall phylloxera.
The banded hickory borer is found on hickories. Some fruits are difficult to categorize. Hickory nuts and walnuts in the Juglandaceae family grow within an outer husk. "Tryma" is a specialized term for such nut-like drupes. Hickory wood is hard, stiff and shock resistant. There are woods that are stronger than hickory and woods that are harder, but the combination of strength, toughness and stiffness found in hickory wood is not found in any other commercial wood, it is used for tool handles, wheel spokes, drumsticks, lacrosse stick handles, golf club shafts, the bottom of skis, walking sticks, for punitive use as a switch, as a cane-like hickory stick in schools and use by parents. Paddles are made from hickory; this property of hickory wood has left a trace in some Native American languages: in Ojibwe, hickory is called mitigwaabaak, a compound of mitigwaab "bow" and the final -aakw "hardwood tree". Baseball bats were made of hickory, but are now more made of ash. Hickory is replacing ash. Hickory was extensively used for the construction of early aircraft.
Hickory is highly prized for wood-burning stoves and chimineas because of its high energy content. Hickory wood is a preferred type for smoking cured meats. In the Southern United States, hickory is popular for cooking barbecue, as hickory grows abundantly in the region and adds flavor to the meat. Hickory is sometimes used for wood flooring due to its durability in resisting character. Hickory wood is not noted for rot resistance. A bark extract from shagbark hickory is used in an edible syrup similar