The Niobrara River is a tributary of the Missouri River 568 miles long, running through the U. S. states of Nebraska. The river drains one of the most arid sections of the Great Plains, has a low flow for a river of its length; the Niobrara's watershed includes the northern tier of Nebraska Sandhills, a small south-central section of South Dakota, as well as a small area of eastern Wyoming. The river rises in southern Niobrara County; the Niobrara flows east as an intermittent stream past Lusk and southeast into northwestern Nebraska. It flows southeast across the Pine Ridge country of Sioux County east through Agate Fossil Beds National Monument, past Marsland, through Box Butte Reservoir; the stream flows east across northern Nebraska, near the northern edge of the Sandhills and past Valentine. It is joined by the Snake River about 13 miles southwest of Valentine. In north-central Nebraska it is joined by the Keya Paha River 6 miles west of Butte; the river joins the Missouri northwest of Niobrara in northern Knox County, just upstream of Lewis and Clark Lake.
Its total drainage basin is about 11,580 square miles. Although the annual runoff is low relative to the size of its drainage basin, the Niobrara has a stronger and more consistent flow than many other streams in the region. An estimated 70 percent of the river's water results from seepage from the Ogallala Aquifer that underlies the area, with the remaining 30 percent from precipitation; the river is lowest in early fall. Low flows in late summer and fall are the result of large irrigation diversions; the Niobrara's average discharge between 1958 and 2013, measured at the U. S. Geological Survey stream gage at Verdel, Nebraska, 14.8 miles above the mouth, is 1,757 cubic feet per second. The highest flow recorded was 39,100 cubic feet per second on March 27, 1960; the lowest daily mean was 102 cubic feet per second on November 13, 1960. The lower Niobrara valley is the traditional home of the Ponca tribe of Native Americans. Between 1861 and 1882, the stretch of the Niobrara River from the mouth of the Keya Paha to its confluence with the Missouri marked the boundary between Nebraska and the Dakota Territory.
A 76-mile stretch of the Niobrara River in central Nebraska, from the town of Valentine east to Nebraska State Highway 137, has been designated as the Niobrara National Scenic River since 1991. It is managed by the Department of the Interior to protect the water quality, paleontologic, fish & wildlife and recreation values. Most of the lands within the boundary of the National Scenic River are, will remain, in private ownership. Management is based upon working with private, county and federal landowners and stakeholders to coordinate protection of the river while ensuring a quality experience for river visitors; the U. S. Fish and Wildlife Service manages the 9 miles of river that flow through the Fort Niobrara Refuge for wilderness and wildlife habitat, but allows recreation downstream from Cornell Dam; the National Park Service manages the remaining 67 miles, acting as a facilitator for resource protection by landowners and river users, providing law enforcement and visitor education services, coordinating resource management activities.
The Box Butte Dam, completed in 1946 by the U. S. Bureau of Reclamation, is the only major dam on the Niobrara River proper. Located in Dawes County in western Nebraska, the dam is part of the Mirage Flats Project, which irrigates 11,670 acres on the north side of the Niobrara River. Dunlap Diversion Dam, 8 miles below Box Butte, diverts water through a 13-mile canal to the farmland; the Snake River tributary is impounded by the Merritt Dam and irrigates about 34,540 acres in the area of Valentine, Nebraska. The project is part of the Ainsworth Unit of the Pick-Sloan Missouri Basin Program operated by the USBR. Cornell Dam, built in 1915 at the confluence of Minnechaduza Creek near Valentine, generated power until 1985; the following year the dam was acquired by the U. S. Department of the Interior. Although decommissioned, the dam remains standing; the feasibility of removing the defunct dam has been studied, although the accumulation of sediment behind the dam, which may include high levels of chemicals from pesticides, may be harmful to the river environment if released.
Spencer Dam, about 50 miles from the mouth of the Niobrara, was the last operational hydroelectric plant on the river. The dam was operated by the Nebraska Public Power District, it includes two Westinghouse generators, with a combined capacity of 3,000 KW. In a 2015 agreement with Nebraska local and state government entities, NPPD agreed to decommission the dam in 2017; the dam was breached by flooding caused by a March 2019 storm. In the Cheyenne language, the river is Hisse Yovi Yoe, meaning "surprise river". Niobrara National Scenic River Niobrara State Park, located at the confluence of the Niobrara and Missouri Rivers Smith Falls Fort Niobrara, a U. S. Army outpost Fort Niobrara National Wildlife Refuge Samuel R. McKelvie National Forest Box Butte Reservoir Agate Fossil Beds National Monument List of longest rivers of the United States List of rivers of the United States List of Nebraska rivers List of Wyoming rivers Niobrara Na
Bouteloua gracilis is a long-lived, warm-season perennial grass, native to North America. It is most found from Alberta, east to Manitoba and south across the Rocky Mountains, Great Plains, U. S. Midwest states, onto the northern Mexican Plateau in Mexico. Blue grama accounts for most of the net primary productivity in the shortgrass prairie of the central and southern Great Plains, it is a greyish, low-growing, drought-tolerant grass with limited maintenance. Blue grama grows on a wide array of topographic positions, in a range of well-drained soil types, from fine- to coarse-textured. Blue grama has 1 to 10 in long; the overall height of the plant is 6 to 12 in at maturity. The flowering stems. At the top are one to four two, comb-like spikes, which extend out at a sharp angle from the flowering stem; each spike has 20 to 90 spikelets. Each spikelet is 5 to 6 mm long, has one fertile floret and one or two reduced sterile ones. Below the florets are two glumes, one 1.5 to 3 mm long and the other 3.5 to 6 mm long.
The fertile floret has a lemma 5 to 5.5 mm long, with three short awns at the tip, the sterile floret has a lemma about 2 mm long with three awns about 5 mm long. If pollinated, the fertile floret produces an oblong-elliptic brown seed 2.5 to 3 mm long. When the seed is mature, the whole spikelet detaches, except for the two glumes; the roots grow 12 to 18 in outwards, 3 to 6.5 ft deep. Blue grama is established from seed, but depends more on vegetative reproduction via tillers. Seed production is slow, depends on soil moisture and temperature. Seeds dispersed by wind only reach a few meters. Seedling establishment and growth are greatest when isolated from neighboring adult plants, which exploit water in the seedling's root zone. Successful establishment requires a modest amount of soil moisture during the extension and development of adventitious roots. Established plants are grazing-, cold-, drought-tolerant, though prolonged drought leads to a reduction in root number and extent, they employ an opportunistic water-use strategy using water when available, becoming dormant during less-favorable conditions.
In terms of successional status, blue grama is a late seral to climax species. Recovery following disturbance depends on the type and extent of the disturbance. Blue grama is valued as forage. B. gracilis is grown by the horticulture industry, used in perennial gardens and native plant landscaping, habitat restoration projects, residential and highway erosion control. Blue grama flowers are used in dried flower arrangements. Blue grama is the state grass of New Mexico, it is listed as an endangered species in Illinois. Among the Zuni people, the grass bunches are tied together and the severed end is used as a hairbrush, the other as a broom. Bunches are used to strain goat's milk; the Costanoan, or Ohlone, use. The Navajo use it as sheep and horse feed
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 natural monument is a natural or natural/cultural feature of outstanding or unique value because of its inherent rarity, representative of aesthetic qualities or cultural significance. Under World Commission on Protected Areas guidelines, natural monuments are level III, described as: "Areas are set aside to protect a specific natural monument, which can be a landform, sea mount, submarine cavern, geological feature such as a cave or a living feature such as an ancient grove, they are quite small protected areas and have high visitor value."This is a lower level of protection than level II and level I. The European Environment Agency's guidelines for selection of a natural monument are: The area should contain one or more features of outstanding significance. Appropriate natural features include waterfalls, craters, fossil beds, sand dunes and marine features, along with unique or representative fauna and flora; the area should be large enough to protect the integrity of the feature and its related surroundings.
Natural monument signs selection IUCN Protected Area Management Categories: Category III Natural Monument or Feature U. S. National Monument World Conservation Union A-Z of Areas of Biodiversity Importance: Natural Monument or Feature Natural Monuments in Brazil
Evolution of the horse
The evolution of the horse, a mammal of the family Equidae, occurred over a geologic time scale of 50 million years, transforming the small, dog-sized, forest-dwelling Eohippus into the modern horse. Paleozoologists have been able to piece together a more complete outline of the evolutionary lineage of the modern horse than of any other animal. Much of this evolution took place in North America, where horses originated but became extinct about 10,000 years ago; the horse belongs to the order Perissodactyla, the members of which all share hooved feet and an odd number of toes on each foot, as well as mobile upper lips and a similar tooth structure. This means that horses share a common ancestry with rhinoceroses; the perissodactyls arose in the late Paleocene, less than 10 million years after the Cretaceous–Paleogene extinction event. This group of animals appears to have been specialized for life in tropical forests, but whereas tapirs and, to some extent, retained their jungle specializations, modern horses are adapted to life on drier land, in the much harsher climatic conditions of the steppes.
Other species of Equus are adapted to a variety of intermediate conditions. The early ancestors of the modern horse walked on several spread-out toes, an accommodation to life spent walking on the soft, moist grounds of primeval forests; as grass species began to appear and flourish, the equids' diets shifted from foliage to grasses, leading to larger and more durable teeth. At the same time, as the steppes began to appear, the horse's predecessors needed to be capable of greater speeds to outrun predators; this was attained through the lengthening of limbs and the lifting of some toes from the ground in such a way that the weight of the body was placed on one of the longest toes, the third. Wild horses were known since prehistory from central Asia to Europe, with domestic horses and other equids being distributed more in the Old World, but no horses or equids of any type were found in the New World when European explorers reached the Americas; when the Spanish colonists brought domestic horses from Europe, beginning in 1493, escaped horses established large feral herds.
In the 1760s, the early naturalist Buffon suggested this was an indication of inferiority of the New World fauna, but reconsidered this idea. William Clark's 1807 expedition to Big Bone Lick found "leg and foot bones of the Horses", which were included with other fossils sent to Thomas Jefferson and evaluated by the anatomist Caspar Wistar, but neither commented on the significance of this find; the first Old World equid fossil was found in the gypsum quarries in Montmartre, Paris, in the 1820s. The tooth was sent to the Paris Conservatory, where it was identified by Georges Cuvier, who identified it as a browsing equine related to the tapir, his sketch of the entire animal matched skeletons found at the site. During the Beagle survey expedition, the young naturalist Charles Darwin had remarkable success with fossil hunting in Patagonia. On 10 October 1833, at Santa Fe, Argentina, he was "filled with astonishment" when he found a horse's tooth in the same stratum as fossil giant armadillos, wondered if it might have been washed down from a layer, but concluded this was "not probable".
After the expedition returned in 1836, the anatomist Richard Owen confirmed the tooth was from an extinct species, which he subsequently named Equus curvidens, remarked, "This evidence of the former existence of a genus, which, as regards South America, had become extinct, has a second time been introduced into that Continent, is not one of the least interesting fruits of Mr. Darwin's palæontological discoveries."In 1848, a study On the fossil horses of America by Joseph Leidy systematically examined Pleistocene horse fossils from various collections, including that of the Academy of Natural Sciences, concluded at least two ancient horse species had existed in North America: Equus curvidens and another, which he named Equus americanus. A decade however, he found the latter name had been taken and renamed it Equus complicatus. In the same year, he was introduced by Owen to Darwin; the original sequence of species believed to have evolved into the horse was based on fossils discovered in North America in the 1870s by paleontologist Othniel Charles Marsh.
The sequence, from Eohippus to the modern horse, was popularized by Thomas Huxley and became one of the most known examples of a clear evolutionary progression. The horse's evolutionary lineage became a common feature of biology textbooks, the sequence of transitional fossils was assembled by the American Museum of Natural History into an exhibit that emphasized the gradual, "straight-line" evolution of the horse. Since as the number of equid fossils has increased, the actual evolutionary progression from Eohippus to Equus has been discovered to be much more complex and multibranched than was supposed; the straight, direct progression from the former to the latter has been replaced by a more elaborate model with numerous branches in different directions, of which the modern horse is only one of many. George Gaylord Simpson in 1951 first recognized that the modern horse was not the "goal" of the entire lineage of equids, but is the only genus of the many horse lineages to survive. Detailed fossil information on the distribution and rate of change of new equid species has revealed that the progression between species was not as smooth and consistent as was once believed.
Although some transitions, such as that of Dinohippus to Equus, were indeed gradual progressions, a number of others, such as that of Epihippus to Mesohippus, were abrupt in geologic time, taking place over only a few million ye
Erysimum is a genus of flowering plants in the cabbage family. It includes about 180 species of many wild forms; the genus Cheiranthus is sometimes included here in part. Erysimum has since the early 21st century been ascribed to a monogeneric cruciferous tribe, characterised by sessile, stellate and/or malpighiaceous trichomes, yellow to orange flowers and multiseeded siliques. Wallflowers are herbaceous perennials or sub-shrubs; the perennial species are short-lived and in cultivation treated as biennials. Most species have stems erect, somewhat winged, canescent with an indumentum of bifid hairs 25 ± 53 cm × 2–3 mm in size, t-shaped trichomes; the leaves are sessile. The lower leaves are linear to oblanceolate pinnatifid with backwardly directed lobes, acute, 50–80 mm × 0.5–3 mm. Stem leaves are linear, all canescent with 2-fid hairs. Flowering occurs during summer. One species, Erysimum semperflorens, native to Morocco and Algeria, has white flowers; the floral pedicel ranges from 4 to 7 mm. Four free sepals somewhat saccate, light green, 5–7 mm × 1.5–2 mm.
The genus name Erysimum is derived from the Greek word'Eryo' meaning to drag. Wallflowers are native to southwest Asia, the Mediterranean, Africa and North America through Costa Rica. Many wallflowers are endemic to small areas, such as: E. aetnense E. franciscanum Erysimum kykkoticum E. moranii E. nevadense E. scoparium E. teretifolium Most wallflower garden cultivars are derived from E. cheiri, from southern Europe. They are attacked by fungal and bacterial disease, so they are best grown as biennials and discarded after flowering, they are susceptible to clubroot, a disease of Brassicaceae. Growth is best in dry soils with good drainage, they are grown in loose wall mortar, hence the vernacular name. There is a wide range of flower color in the warm spectrum, including white, orange, pink, maroon and brown; the flowers, appearing in spring have a strong fragrance. Wallflowers are associated in spring bedding schemes with tulips and forget-me-nots; the cultivar'Bowles's Mauve' has gained the Royal Horticultural Society's Award of Garden Merit.
Erysimum species are used as food plants by the larvae of some Lepidoptera species including the Garden Carpet. In addition, some species of weevils, like Ceutorhynchus chlorophanus, live inside the fruits feeding on the developing seeds. Many species of beetles and grasshoppers eat the leaves and stalks; some mammalian herbivores, for example Mule Deer in North America, Argali in Mongolia, Red Deer in Central Europe, or Spanish Ibex in the Iberian Peninsula, feed on wallflower flowering and fruiting stalks. Most wallflowers are pollinator-generalists, their flowers being visited by many different species of bees, bee flies, butterflies and ants. However, there are some specialist species. For example, Erysimum scoparium is pollinated exclusively by Anthophora alluadii. Evoflor, a web page on Erysimum floral evolution webpage of a UK collector of erysimums Herbario del Instituto Pirenaico de Ecología, CSIC Botánica Sistemática, an open web on plants
International Union for Conservation of Nature
The International Union for Conservation of Nature is an international organization working in the field of nature conservation and sustainable use of natural resources. It is involved in data gathering and analysis, field projects and education. IUCN's mission is to "influence and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable". Over the past decades, IUCN has widened its focus beyond conservation ecology and now incorporates issues related to sustainable development in its projects. Unlike many other international environmental organisations, IUCN does not itself aim to mobilize the public in support of nature conservation, it tries to influence the actions of governments and other stakeholders by providing information and advice, through building partnerships. The organization is best known to the wider public for compiling and publishing the IUCN Red List of Threatened Species, which assesses the conservation status of species worldwide.
IUCN has a membership of over 1400 non-governmental organizations. Some 16,000 scientists and experts participate in the work of IUCN commissions on a voluntary basis, it employs 1000 full-time staff in more than 50 countries. Its headquarters are in Switzerland. IUCN has observer and consultative status at the United Nations, plays a role in the implementation of several international conventions on nature conservation and biodiversity, it was involved in establishing the World Wide Fund for Nature and the World Conservation Monitoring Centre. In the past, IUCN has been criticized for placing the interests of nature over those of indigenous peoples. In recent years, its closer relations with the business sector have caused controversy. IUCN was established in 1948, it was called the International Union for the Protection of Nature and the World Conservation Union. Establishment IUCN was established on 5 October 1948, in Fontainebleau, when representatives of governments and conservation organizations signed a formal act constituting the International Union for the Protection of Nature.
The initiative to set up the new organisation came from UNESCO and from its first Director General, the British biologist Julian Huxley. The objectives of the new Union were to encourage international cooperation in the protection of nature, to promote national and international action and to compile and distribute information. At the time of its founding IUPN was the only international organisation focusing on the entire spectrum of nature conservation Early years: 1948–1956 IUPN started out with 65 members, its secretariat was located in Brussels. Its first work program focused on saving species and habitats and applying knowledge, advancing education, promoting international agreements and promoting conservation. Providing a solid scientific base for conservation action was the heart of all activities. IUPN and UNESCO were associated, they jointly organized the 1949 Conference on Protection of Nature. In preparation for this conference a list of gravely endangered species was drawn up for the first time, a precursor of the IUCN Red List of Threatened Species.
In the early years of its existence IUCN depended entirely on UNESCO funding and was forced to temporarily scale down activities when this ended unexpectedly in 1954. IUPN was successful in engaging prominent scientists and identifying important issues such as the harmful effects of pesticides on wildlife but not many of the ideas it developed were turned into action; this was caused by unwillingness to act on the part of governments, uncertainty about the IUPN mandate and lack of resources. In 1956, IUPN changed its name to International Union for Conservation of Nature and Natural Resources. Increased profile and recognition: 1956–1965 In the 1950s and 1960s Europe entered a period of economic growth and formal colonies became independent. Both developments had impact on the work of IUCN. Through the voluntary involvement of experts in its Commissions IUCN was able to get a lot of work done while still operating on a low budget, it established links with the Council of Europe. In 1961, at the request of United Nations Economic and Social Council, the United Nations Economic and Social Council, IUCN published the first global list of national parks and protected areas which it has updated since.
IUCN's best known publication, the Red Data Book on the conservation status of species, was first published in 1964. IUCN began to play a part in the development of international treaties and conventions, starting with the African Convention on the Conservation of Nature and Natural Resources. Environmental law and policy making became a new area of expertise. Africa was the focus of many of the early IUCN conservation field projects. IUCN supported the ‘Yellowstone model’ of protected area management, which restricted human presence and activity in order to protect nature. IUCN and other conservation organisations were criticized for protecting nature against people rather than with people; this model was also applied in Africa and played a role in the decision to remove the Maasai people from Serengeti National Park and the Ngorongoro Conservation Area. To establish a stable financial basis for its work, IUCN participated in setting up the World Wildlife Fund