A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, petrified wood, coal, DNA remnants; the totality of fossils is known as the fossil record. Paleontology is the study of fossils: their age, method of formation, evolutionary significance. Specimens are considered to be fossils if they are over 10,000 years old; the oldest fossils are around 3.48 billion years old to 4.1 billion years old. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils; the development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization, including permineralization and molds, authigenic mineralization and recrystallization, adpression and bioimmuration.
Fossils vary in size from one-micrometre bacteria to dinosaurs and trees, many meters long and weighing many tons. A fossil preserves only a portion of the deceased organism that portion, mineralized during life, such as the bones and teeth of vertebrates, or the chitinous or calcareous exoskeletons of invertebrates. Fossils may consist of the marks left behind by the organism while it was alive, such as animal tracks or feces; these types of fossil are called trace ichnofossils, as opposed to body fossils. Some fossils are called chemofossils or biosignatures; the process of fossilization varies according to external conditions. Permineralization is a process of fossilization; the empty spaces within an organism become filled with mineral-rich groundwater. Minerals precipitate from the groundwater; this process can occur in small spaces, such as within the cell wall of a plant cell. Small scale permineralization can produce detailed fossils. For permineralization to occur, the organism must become covered by sediment soon after death, otherwise decay commences.
The degree to which the remains are decayed when covered determines the details of the fossil. Some fossils consist only of skeletal teeth; this is a form of diagenesis. In some cases, the original remains of the organism dissolve or are otherwise destroyed; the remaining organism-shaped hole in the rock is called an external mold. If this hole is filled with other minerals, it is a cast. An endocast, or internal mold, is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail or the hollow of a skull; this is a special form of mold formation. If the chemistry is right, the organism can act as a nucleus for the precipitation of minerals such as siderite, resulting in a nodule forming around it. If this happens before significant decay to the organic tissue fine three-dimensional morphological detail can be preserved. Nodules from the Carboniferous Mazon Creek fossil beds of Illinois, USA, are among the best documented examples of such mineralization.
Replacement occurs. In some cases mineral replacement of the original shell occurs so and at such fine scales that microstructural features are preserved despite the total loss of original material. A shell is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, as from aragonite to calcite. Compression fossils, such as those of fossil ferns, are the result of chemical reduction of the complex organic molecules composing the organism's tissues. In this case the fossil consists of original material, albeit in a geochemically altered state; this chemical change is an expression of diagenesis. What remains is a carbonaceous film known as a phytoleim, in which case the fossil is known as a compression. However, the phytoleim is lost and all that remains is an impression of the organism in the rock—an impression fossil. In many cases, however and impressions occur together. For instance, when the rock is broken open, the phytoleim will be attached to one part, whereas the counterpart will just be an impression.
For this reason, one term covers the two modes of preservation: adpression. Because of their antiquity, an unexpected exception to the alteration of an organism's tissues by chemical reduction of the complex organic molecules during fossilization has been the discovery of soft tissue in dinosaur fossils, including blood vessels, the isolation of proteins and evidence for DNA fragments. In 2014, Mary Schweitzer and her colleagues reported the presence of iron particles associated with soft tissues recovered from dinosaur fossils. Based on various experiments that studied the interaction of iron in haemoglobin with blood vessel tissue they proposed that solution hypoxia coupled with iron chelation enhances the stability and preservation of soft tissue and provides the basis for an explanation for the unforeseen preservation of fossil soft tissues. However, a older study based on eight taxa ranging in time from the Devonian to the Jurassic found that reasonably well-preserved fibrils that represent collagen were preser
A calcareous glade is an ecological community, found in the central eastern United States. Calcareous glades occur where bedrock such as limestone occurs near or at the surface, have shallow and little soil development; because of the shallow soil and the extreme conditions created by it, trees are unable to grow in the glades. This creates a habitat, sunny and hot. Calcareous glade vegetation is more similar to that of a desert habitat than a grassland, being dominated by small spring annuals with occasional geophytic or succulent perennials; the usage of the words "glades" and "barrens" to describe dry, rocky communities in the United States is not uniform, the terms are used interchangeably. Calcareous glade communities can intergrade with dry rocky prairies in sloping habitats. Due to their unsuitability for agriculture, glade communities have survived to the present day at a higher rate than deeper-soil prairie communities; the Interior Low Plateau is a region in the Upper South, known for its calcareous glade communities.
This region is centered in Tennessee and Kentucky, extends into northern Alabama, southern Illinois, southern Indiana, southern Ohio. These glades are best developed in the area of the Central Basin in Tennessee, where they are geographically widespread and harbor high levels of endemism. Outside of the Central Basin, calcareous glades are found in lower numbers throughout the Interior Low Plateau, species endemism is reduced. Glades in the Interior Low Plateaus are characterized by species such as one-flower gladecress, limestone skullcap, widow's-cross stonecrop, poverty dropseed and glade violet; the limestone glades of the Central Basin in Tennessee are called "cedar glades". The name comes from the abundance of eastern redcedar that occurs on the margins of the glades or in cracks in the bedrock where the roots can gain a foothold. Many of the characteristic plants that grow in the limestone glades of the Central Basin are endemics that occur nowhere else, or disjunct populations of plants that are widespread in the prairies of the central U.
S. Some species with restricted ranges that occur in the glades of the Central Basin include the Tennessee coneflower, Pyne's ground plum, leafy prairie clover, Tennessee milkvetch, Nashville breadroot, limestone fameflower; these glades can be saturated with water in the winter and spring, leading to "xerohydirc" conditions. The central basin of Tennessee is one of the largest areas containing limestone glades; because of the rapid growth of metropolitan Nashville and the surrounding cities of Murfreesboro and Lebanon, many of the limestone glades have been destroyed by development. The State of Tennessee and the Nature Conservancy have established a number of parks and preserves to protect important plant populations. Cedars of Lebanon State Park in Wilson County and Long Hunter State Park in Davidson County both protect substantial limestone glade ecosystems. Calcareous glades are well developed in the Ozark Mountains. In Missouri, the majority of these glades are found on dolomitic limestones, with less than 1% formed from carbonate limestone.
Species indicative of Ozarkian calcareous glade communities include Cheilanthes feei, Echinacea simulata, Heliotropium tenellum, Isoetes butleri, Oenothera macrocarpa, Ophioglossum engelmannii. In Missouri, Physaria filiformis is a species restricted to calcitic limestone glades; the Ridge and Valley region, which extends north from Pennsylvania south to Alabama, has significant calcareous glade communities. These glades have dolomitic soils, resulting in a high magnesium content. In Virgnia, these glades provide habitat for rare magnesiophiles such as Addison's leatherflower, tall larkspur, smooth coneflower, glade wild quinine. At the southern end of the Ridge and Valley in Alabama in Bibb County, species endemism of glade communities peaks; this area, known as a Ketona Dolomite Outcrops, was first recognized as ecologically significant in 1992. Since its discovery, eight new plant taxa to science have been described from this region, in addition to the 60 species of conservation concern found in or around this community.
Endemic species of this area include Castilleja kraliana, Dalea cahaba, Liatris oligocephala, Lithospermum decipiens, Spigelia alabamensis. Center for Cedar Glade Studies at Middle Tennessee State University Common and Endemic Herbaceous Plants of Cedar Glades
Big South Fork National River and Recreation Area
The Big South Fork National River and Recreation Area preserves the Big South Fork of the Cumberland River and its tributaries in northeastern Tennessee and southeastern Kentucky. In addition, the former mining community of Blue Heron is interpreted via signage; the Big South Fork region contains one of the highest concentrations of natural bridges in the eastern United States and the area is located in parts of Scott, Fentress and Morgan counties in Tennessee, McCreary County in Kentucky. Charit Creek Lodge is a wilderness lodge, accessible by trail, located within the park; the Big South Fork was legally designated a Kentucky Wild River by the Kentucky General Assembly through the Office of Kentucky Nature Preserves' Wild Rivers Program. The Big South Fork's most prominent feature is the river gorge cutting through the softer Mississippian age rock beneath the hard Pennsylvanian capstone of the Cumberland Plateau. Water is the most influential agent of geologic change in the Big South Fork region.
Over time water action has left many unique and amazing geologic features ranging from the river gorge with its magnificent bluffs to the natural arches and unusual hoodoos. Due to the substantial amount of annual rainfall of the region and the action of the Cumberland River and surrounding tributaries the water acts to erode the softer Mississippian rock composed of limestone and calcareous sandstone from beneath the much harder and erosion resistant capstone composed of Pennsylvanian sandstone. Flowing water hollows out the softer layers beneath and forms waterfalls and gorges. Where there is hard capstone intact, arches can form creating natural bridges across streams or a dry ravines. Direct erosion widens a joint and forms a cavity below the more resilient rock thus creating a void between the hard capstone and the area below; as result, water eroded. Hoodoos are a intriguing feature occurring in the Big South Fork; these hoodoos form in a similar manner to those found in the western United States.
Where tough capstone still exists on the side of a hill for instance, it prevents the erosion of the softer material below. The result is a formed erect columnar rock where once was located a hill. "Big South Fork NPS Site". National Park Service. Retrieved 2011-08-08. "Big South Fork Landforms". Tom Dunigan. Retrieved 2011-08-08
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, the natural hazards that threaten it; the organization has four major science disciplines, concerning biology, geography and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility; the USGS is a bureau of the United States Department of the Interior. The USGS employs 8,670 people and is headquartered in Reston, Virginia; the USGS has major offices near Lakewood, Colorado, at the Denver Federal Center, Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world." The agency's previous slogan, adopted on the occasion of its hundredth anniversary, was "Earth Science in the Public Service." Since 2012, the USGS science focus is directed at six topical "Mission Areas", namely Climate and Land Use Change, Core Science Systems, Ecosystems and Minerals and Environmental Health, Natural Hazards, Water.
In December 2012, the USGS split the Energy and Minerals and Environmental Health Mission Area resulting in seven topical Mission Areas, with the two new areas being: Energy and Minerals and Environmental Health. Administratively, it is divided into six Regional Units. Other specific programs include: Earthquake Hazards Program monitors earthquake activity worldwide; the National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location and magnitude of global earthquakes. The USGS runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System; the USGS informs authorities, emergency responders, the media, the public, both domestic and worldwide, about significant earthquakes. It maintains long-term archives of earthquake data for scientific and engineering research, it conducts and supports research on long-term seismic hazards. USGS has released the UCERF California earthquake forecast.
As of 2005, the agency is working to create a National Volcano Early Warning System by improving the instrumentation monitoring the 169 volcanoes in U. S. territory and by establishing methods for measuring the relative threats posed at each site. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time; the USGS collaborates with Canadian and Mexican government scientists, along with the Commission for Environmental Cooperation, to produce the North American Environmental Atlas, used to depict and track environmental issues for a continental perspective. The USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online. National Climate Change and Wildlife Science Center implements partner-driven science to improve understanding of past and present land use change, develops relevant climate and land use forecasts, identifies lands and communities that are most vulnerable to adverse impacts of change from the local to global scale.
Since 1962, the Astrogeology Research Program has been involved in global and planetary exploration and mapping. In collaboration with Stanford University, the USGS operates the USGS-Stanford Ion Microprobe Laboratory, a world-class analytical facility for U--Pb geochronology and trace element analyses of minerals and other earth materials. USGS operates a number of water related programs, notably the National Streamflow Information Program and National Water-Quality Assessment Program. USGS Water data is publicly available from their National Water Information System database; the USGS operates the National Wildlife Health Center, whose mission is "to serve the nation and its natural resources by providing sound science and technical support, to disseminate information to promote science-based decisions affecting wildlife and ecosystem health. The NWHC provides information, technical assistance, research and leadership on national and international wildlife health issues." It is the agency responsible for surveillance of H5N1 avian influenza outbreaks in the United States.
The USGS runs 17 biological research centers in the United States, including the Patuxent Wildlife Research Center. The USGS is investigating collaboration with the social networking site Twitter to allow for more rapid construction of ShakeMaps; the USGS produces several national series of topographic maps which vary in scale and extent, with some wide gaps in coverage, notably the complete absence of 1:50,000 scale topographic maps or their equivalent. The largest and best-known topographic series is the 7.5-minute, 1:24,000 scale, quadrangle, a non-metric scale unique to the United States. Each of these maps covers an area bounded by two lines of latitude and two lines of longitude spaced 7.5 minutes apart. Nearly 57,000 individual maps in this series cover the 48 contiguous states, Hawaii, U. S. territories, areas of Alaska near Anchorage and Prudhoe Bay. The area covered by each map varies with the latitude of its represented location due to convergence of the meridians. At lower latitudes, near 30° north, a 7.5-minute quadrangle contains an area of about 64 square miles.
At 49° north latitude, 49 square miles are contained within a quadrangle of that size. As a unique non-metric map scale, the 1:24,000 scale requires a separate and specialized romer scale for pl
Daniel Boone was an American pioneer, explorer and frontiersman, whose frontier exploits made him one of the first folk heroes of the United States. Boone is most famous for his settlement of what is now Kentucky, it was still considered part of Virginia but was on the western side of the Appalachian Mountains from most European-American settlements. As a young adult, Boone supplemented his farm income by hunting and trapping game, selling their pelts in the fur market. Through this occupational interest, Boone first learned the easy routes to the area. Despite some resistance from American Indian tribes such as the Shawnee, in 1775, Boone blazed his Wilderness Road from North Carolina and Tennessee through Cumberland Gap in the Cumberland Mountains into Kentucky. There, he founded the village of Boonesborough, one of the first American settlements west of the Appalachians. Before the end of the 18th century, more than 200,000 Americans migrated to Kentucky/Virginia by following the route marked by Boone.
Boone served as a militia officer during the Revolutionary War, which, in Kentucky, was fought between the American settlers and British-allied Native Americans, who hoped to expel the Americans. Boone was captured by Shawnee warriors in 1778, he alerted Boonesborough that the Shawnee were planning an attack. Although outnumbered, Americans repelled the Shawnee warriors in the Siege of Boonesborough. Boone was elected to the first of his three terms in the Virginia General Assembly during the Revolutionary War, he fought in the Battle of Blue Licks in 1782. Blue Licks, a Shawnee victory over the Patriots, was one of the last battles of the Revolutionary War, coming after the main fighting ended in October 1781. Following the war, Boone worked as a surveyor and merchant, but fell into debt through failed Kentucky land speculation. Frustrated with the legal problems resulting from his land claims, in 1799, Boone emigrated to eastern Missouri, where he spent most of the last two decades of his life.
Boone remains an iconic figure in American history. He was a legend in his own lifetime after an account of his adventures was published in 1784, framing him as the typical American frontiersman. After his death, he was the subject of heroic tall tales and works of fiction, his adventures—real and legendary—were influential in creating the archetypal frontier hero of American folklore. In American popular culture, he is remembered as one of the foremost early frontiersmen; the epic Daniel Boone mythology overshadows the historical details of his life. Daniel Boone was of English West Welsh ancestry; because the Gregorian calendar was adopted during his lifetime, Boone's birth date is sometimes given as November 2, 1734, although Boone used the October date. The Boone family belonged to the Religious Society of Friends, called "Quakers", were persecuted in England for their dissenting beliefs. Daniel's father, Squire Boone emigrated from the small town of Bradninch, Devon to Pennsylvania in 1713, to join William Penn's colony of dissenters.
Squire Boone's parents, George Boone III and Mary Maugridge, followed their son to Pennsylvania in 1717, in 1720 built a log cabin at Boonecroft. In 1720, Squire Boone, who worked as a weaver and a blacksmith, married Sarah Morgan. Sarah's family were Quakers from Wales, had settled in 1708 in the area which became Towamencin Township of Montgomery County. In 1731, the Boones moved to Exeter Township in the Oley Valley of Berks County, near the modern city of Reading. There they built a log cabin preserved today as the Daniel Boone Homestead. Daniel Boone was born there, the sixth of eleven children; the Daniel Boone Homestead is four miles from the Mordecai Lincoln House, making the Squire Boone family neighbors of Mordecai Lincoln, the great-great-grandfather of future president Abraham Lincoln. Mordecai's son named Abraham, married Ann Boone, a first cousin of Daniel. Daniel Boone spent his early years on what was the edge of the frontier. Several Lenape Indian villages were nearby; the pacifist Pennsylvania Quakers had good relations with the Native Americans, but the steady growth of the white population compelled many Indians to move further west.
Boone was given his first rifle at the age of 12. He learned to hunt from the Lenape. Folk tales have emphasized Boone's skills as a hunter. In one story, the young Boone was hunting in the woods with some other boys, when the howl of a panther scattered all but Boone, he calmly shot the predator through the heart just as it leaped at him. The validity of this claim is contested, but the story was told so that it became part of his popular image. In Boone's youth, his family became a source of controversy in the local Quaker community when two of the oldest children married outside the endogamous community, in present-day Lower Gwynedd Township, Pennsylvania. In 1742, Boone's parents were compelled to apologize publicly after their eldest child, married John Willcockson, a "worldling"; because the young couple had "kept company", they were considered "married without benefit of clergy". When the Boones' oldest son Israel married a "worldling" in 1747, Squire Boone stood by him. Both men were expelled from the Quakers.
In 1750, Squire Boone moved the family to North Carolina. Daniel Boone did not attend church again, he had all of his children baptized. The Boones