The Brooks Range ( Gwich'in : Gwazhał ) is a mountain range in far northern North America stretching some 700 miles (1,100 km) from west to east across northern Alaska into Canada 's Yukon Territory . Reaching a peak elevation of 8,976 feet (2,736 m) on Mount Isto , the range is believed to be approximately 126 million years old.
121-871: In the United States, these mountains are considered a subrange of the Rocky Mountains , whereas in Canada they are considered separate, as the northern border of the Rocky Mountains is considered to be the Liard River far to the south in the province of British Columbia . While the range is mostly uninhabited, the Dalton Highway and Trans-Alaska Pipeline System run through the Atigun Pass (1,415 m, 4,643 ft) on their way to
242-526: A European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, where they were called " montagnes de Roche ". Another name given to the place by the Cree is ᐊᓭᓂᐓᒉ Aseniwuche . The Rocky Mountains are the easternmost portion of the expansive North American Cordillera . They are often defined as stretching from the Liard River in British Columbia south to the headwaters of
363-557: A clade called Arachnomorpha , while others consider them to be more closely related to Mandibulata (which contains insects , crustaceans and myriapods ) as part of a clade called Antennulata . The earliest trilobites known from the fossil record are redlichiids and ptychopariid bigotinids dated to around 520 million years ago. Contenders for the earliest trilobites include Profallotaspis jakutensis (Siberia), Fritzaspis spp. (western USA), Hupetina antiqua (Morocco) and Serrania gordaensis (Spain). Trilobites appeared at
484-572: A high and 3 °C (37 °F) as a low. During the winter the average high is −22 °C (−8 °F) while the average low is −30 °C (−22 °F). Polar amplification is a force experienced in this region as global temperatures are rising. The northern and western regions of Alaska, where the Brooks Range lies, is experiencing a warming rate twice that of southeastern Alaska. The Brooks Range has experienced an increase in average summer temperature between 4.2 °F and 5.8 °F between
605-526: A lattice of chitin , and is curled round the lower edge to produce a small fringe called the "doublure". Their appendages and soft underbelly were non-mineralized. Three distinctive tagmata (sections) are present: cephalon (head); thorax (body) and pygidium (tail). As might be expected for a group of animals comprising c. 5,000 genera, the morphology and description of trilobites can be complex. Despite morphological complexity and an unclear position within higher classifications, there are
726-523: A mixture of white pine, fir, and spruce that appear as shrub-like krummholz . Finally, rivers and canyons can create a unique forest zone in more arid parts of the mountain range. The Rocky Mountains are an important habitat for a great deal of well-known wildlife, such as wolves , elk , moose , mule and white-tailed deer , pronghorn , mountain goats , bighorn sheep , badgers , black bears , grizzly bears , coyotes , lynxes , cougars , and wolverines . North America's largest herds of elk are in
847-519: A natant (unattached) hypostome . The most recently recognized of the nine trilobite orders, Harpetida, was erected in 2002. The progenitor of order Phacopida is unclear. When trilobites are found, only the exoskeleton is preserved (often in an incomplete state) in all but a handful of locations. A few locations ( Lagerstätten ) preserve identifiable soft body parts (legs, gills, musculature & digestive tract) and enigmatic traces of other structures (e.g. fine details of eye structure) as well as
968-427: A new order, Eodiscida. Over 20,000 species of trilobite have been described. Despite their rich fossil record with thousands of described genera found throughout the world, the taxonomy and phylogeny of trilobites have many uncertainties. Except possibly for the members of the orders Phacopida and Lichida (which first appear during the early Ordovician ), nine of the eleven trilobite orders appear prior to
1089-430: A number of characteristics which distinguish the trilobites from other arthropods: a generally sub-elliptical, dorsal , chitinous exoskeleton divided longitudinally into three distinct lobes (from which the group gets its name); having a distinct, relatively large head shield (cephalon) articulating axially with a thorax comprising articulated transverse segments, the hindmost of which are almost invariably fused to form
1210-640: A roughly equivalent time in Laurentia , Siberia and West Gondwana . All Olenellina lack facial sutures (see below ), and this is thought to represent the original state. The earliest sutured trilobite found so far ( Lemdadella ), occurs almost at the same time as the earliest Olenellina, suggesting the trilobites origin lies before the start of the Atdabanian, but without leaving fossils. Other groups show secondary lost facial sutures, such as all Agnostina and some Phacopina . Another common feature of
1331-828: A similar relationship to tourism promotions by the Great Northern Railway . While settlers filled the valleys and mining towns, conservation and preservation ethics began to take hold. U.S. President Benjamin Harrison established several forest reserves in the Rocky Mountains in 1891–1892. In 1905, U.S. President Theodore Roosevelt extended the Medicine Bow Forest Reserve to include the area now managed as Rocky Mountain National Park . Economic development began to center on mining, forestry , agriculture, and recreation , as well as on
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#17327910423411452-471: A tail shield ( pygidium ). When describing differences between trilobite taxa , the presence, size, and shape of the cephalic features are often mentioned. During moulting , the exoskeleton generally splits between the head and thorax, which is why so many trilobite fossils are missing one or the other. In most groups facial sutures on the cephalon helped facilitate moulting. Similar to lobsters and crabs , trilobites would have physically "grown" between
1573-573: Is 72 cm (28 in) in length. It was found in 1998 by Canadian scientists in Ordovician rocks on the shores of Hudson Bay . However, a partial specimen of the Ordovician trilobite Hungioides bohemicus found in 2009 in Arouca , Portugal is estimated to have measured when complete 86.5 cm (34.1 in) in length. Only the upper (dorsal) part of their exoskeleton is mineralized, composed of calcite and calcium phosphate minerals in
1694-465: Is a strong indication that novel morphologies were developing very rapidly. Changes within the trilobite fauna during the Ordovician foreshadowed the mass extinction at the end of the Ordovician, allowing many families to continue into the Silurian with little disturbance. Ordovician trilobites were successful at exploiting new environments, notably reefs . The Ordovician mass extinction did not leave
1815-426: Is based on the use of trilobite marker fossils. Trilobites are the state fossils of Ohio ( Isotelus ), Wisconsin ( Calymene celebra ) and Pennsylvania ( Phacops rana ). The 10 most commonly recognized trilobite orders are Agnostida , Redlichiida , Corynexochida , Lichida , Odontopleurida , Phacopida , Proetida , Asaphida , Harpetida and Ptychopariida . In 2020, an 11th order, Trinucleida ,
1936-575: Is best known from these samples preserved similarly to bodies in Pompeii. The French palaeontologist Joachim Barrande (1799–1883) carried out his landmark study of trilobites in the Cambrian, Ordovician and Silurian of Bohemia , publishing the first volume of Système silurien du centre de la Bohême in 1852. The study of Paleozoic trilobites in the Welsh-English borders by Niles Eldredge
2057-494: Is foreshadowed. Some of the genera of Trilobites appearing in the Ordovician include: Most Early Silurian families constitute a subgroup of the Late Ordovician fauna. Few, if any, of the dominant Early Ordovician fauna survived to the end of the Ordovician, yet 74% of the dominant Late Ordovician trilobite fauna survived the Ordovician. Late Ordovician survivors account for all post-Ordovician trilobite groups except
2178-1764: Is found in the Silurian Wenlock Group . This trilobite is featured on the town's coat of arms and was named the Dudley Bug or Dudley Locust by quarrymen who once worked the now abandoned limestone quarries. Llandrindod Wells , Powys , Wales , is another famous trilobite location. The well-known Elrathia kingi trilobite is found in abundance in the Cambrian Wheeler Shale of Utah . Spectacularly preserved trilobite fossils, often showing soft body parts (legs, gills, antennae, etc.) have been found in British Columbia , Canada (the Cambrian Burgess Shale and similar localities); New York , U.S.A. (Ordovician Walcott–Rust quarry , near Russia , and Beecher's Trilobite Bed , near Rome ); China (Lower Cambrian Maotianshan Shales near Chengjiang ); Germany (the Devonian Hunsrück Slates near Bundenbach ) and, much more rarely, in trilobite-bearing strata in Utah (Wheeler Shale and other formations), Ontario , and Manuels River, Newfoundland and Labrador . Sites in Morocco also yield very well-preserved trilobites, many buried in mudslides alive and so perfectly preserved. An industry has developed around their recovery, leading to controversies about practices in restoral. The variety of eye and upper body forms and fragile protuberances
2299-794: Is in the Rocky Mountains and designates the line at which waters flow either to the Atlantic or Pacific Oceans. Triple Divide Peak (2,440 m or 8,020 ft) in Glacier National Park is so named because water falling on the mountain reaches not only the Atlantic and Pacific but Hudson Bay as well. Farther north in Alberta, the Athabasca and other rivers feed the basin of the Mackenzie River , which has its outlet on
2420-706: Is natural gas that arises from coal, either through bacterial action or through exposure to high temperature. Coalbed methane supplies 7 percent of the natural gas used in the U.S. The largest coalbed methane sources in the Rocky Mountains are in the San Juan Basin in New Mexico and Colorado and the Powder River Basin in Wyoming. These two basins are estimated to contain 38 trillion cubic feet of gas. Coalbed methane can be recovered by dewatering
2541-529: Is no surprise that trilobite evolutionary history is marked by a number of extinction events where some groups perished, and surviving groups diversified to fill ecological niches with comparable or unique adaptations. Generally, trilobites maintained high diversity levels throughout the Cambrian and Ordovician periods before entering a drawn-out decline in the Devonian , culminating in the final extinction of
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#17327910423412662-428: Is recorded at the same time as the extinctions, suggesting major environmental upheaval. Notable trilobite genera appearing in the Cambrian include: The Early Ordovician is marked by vigorous radiations of articulate brachiopods, bryozoans, bivalves, echinoderms, and graptolites, with many groups appearing in the fossil record for the first time. Although intra-species trilobite diversity seems to have peaked during
2783-668: The 49th parallel north as the international boundary west from Lake of the Woods to the "Stony Mountains"; the UK and the US agreed to what has since been described as "joint occupancy" of lands further west to the Pacific Ocean. Resolution of the territorial and treaty issues, the Oregon dispute , was deferred until a later time. In 1819, Spain ceded their rights north of the 42nd Parallel to
2904-479: The Alberta–British Columbia foothills forests . The status of most species in the Rocky Mountains is unknown, due to incomplete information. European-American settlement of the mountains has adversely impacted native species. Examples of some species that have declined include western toads , greenback cutthroat trout , white sturgeon , white-tailed ptarmigan , trumpeter swan , and bighorn sheep. In
3025-547: The Apache , Arapaho , Bannock , Blackfoot , Cheyenne , Coeur d'Alene , Kalispel , Crow Nation , Flathead , Shoshone , Sioux , Ute , Kutenai (Ktunaxa in Canada), Sekani , Dunne-za , and others. Paleo-Indians hunted the now-extinct mammoth and ancient bison (an animal 20% larger than modern bison) in the foothills and valleys of the mountains. Like the modern tribes that followed them, Paleo-Indians probably migrated to
3146-517: The Artiopoda , a group of extinct arthropods morphologically similar to trilobites, though only the trilobites had mineralised exoskeletons. Thus, other artiopodans are typically only found in exceptionally preserved deposits, mostly during the Cambrian period. The exact relationships of artiopods to other arthropods is uncertain. They have been considered closely related to chelicerates (which include horseshoe crabs and arachnids ) as part of
3267-759: The Beaufort Sea of the Arctic Ocean. Human population is not very dense in the Rockies, with an average of four people per square kilometer and few cities with over 50,000 people. However, the human population grew rapidly in the Rocky Mountain states between 1950 and 1990. The forty-year statewide increases in population range from 35% in Montana to about 150% in Utah and Colorado. The populations of several mountain towns and communities have doubled in
3388-709: The Bull Lake Glaciation , which began about 150,000 years ago, and the Pinedale Glaciation , which perhaps remained at full glaciation until 15,000–20,000 years ago. All of these geological processes exposed a complex set of rocks at the surface. For example, volcanic rock from the Paleogene and Neogene periods (66 million – 2.6 million years ago) occurs in the San Juan Mountains and in other areas. Millennia of severe erosion in
3509-608: The Canadian Pacific Railway eventually followed the Kicking Horse and Rogers Passes to the Pacific Ocean. Canadian railway officials also convinced Parliament to set aside vast areas of the Canadian Rockies as Jasper , Banff , Yoho , and Waterton Lakes National Parks , laying the foundation for a tourism industry which thrives to this day. Glacier National Park (MT) was established with
3630-902: The Canadian Rockies . The eastern edge of the Rockies rises dramatically above the Interior Plains of central North America, including the Sangre de Cristo Mountains of New Mexico and Colorado , the Front Range of Colorado, the Wind River Range and Big Horn Mountains of Wyoming , the Absaroka - Beartooth ranges and Rocky Mountain Front of Montana and the Clark Range of Alberta . Central ranges of
3751-917: The Canning River and the Firth River across the Alaska - Yukon border. Its southernmost point is near the Albuquerque area adjacent to the Rio Grande rift and north of the Sandia–Manzano Mountain Range . Being the easternmost portion of the North American Cordillera , the Rockies are distinct from the tectonically younger Cascade Range and Sierra Nevada , which both lie farther to its west. The Rockies formed 55 million to 80 million years ago during
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3872-507: The Climax mine, near Leadville, Colorado , was the largest producer of molybdenum in the world. Molybdenum is used in heat-resistant steel in such things as cars and planes. The Climax mine employed over 3,000 workers. The Coeur d'Alene mine of northern Idaho produces silver, lead, and zinc. Canada's largest coal mines are near Fernie, British Columbia and Sparwood , British Columbia; additional coal mines exist near Hinton, Alberta , and in
3993-706: The Columbia District for Britain. The party crossed the Rockies into the Columbia Valley , a region of the Rocky Mountain Trench near present-day Radium Hot Springs , British Columbia, then traveled south. Despite such efforts, in 1846, Britain ceded all claim to Columbia District lands south of the 49th parallel to the United States; as resolution to the Oregon boundary dispute by the Oregon Treaty . Thousands passed through
4114-548: The Harpetida . Silurian and Devonian trilobite assemblages are superficially similar to Ordovician assemblages, dominated by Lichida and Phacopida (including the well-known Calymenina ). A number of characteristic forms do not extend far into the Devonian and almost all the remainder were wiped out by a series of dramatic Middle and Late Devonian extinctions . Three orders and all but five families were exterminated by
4235-517: The Laramide orogeny , in which a number of plates began sliding underneath the North American plate . The angle of subduction was shallow, resulting in a broad belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. At the end of the last ice age , humans began inhabiting
4356-676: The Liard River and east of the Rocky Mountain Trench , and do not extend into Yukon , Northwest Territories or central British Columbia . They are divided into three main groups: the Muskwa Ranges , Hart Ranges (collectively called the Northern Rockies ) and Continental Ranges . Other more northerly mountain ranges of the eastern Canadian Cordillera continue beyond the Liard River valley, including
4477-590: The North Fork Koyukuk River area of the range in 1929. He named Mount Doonerak, explaining "the name Doonerak I took from an Eskimo word which means a spirit or, as they would translate it, a devil." Marshall described the mountain as, a "towering, black, unscalable-looking giant, the highest peak in this section of the Brooks Range." The Brooks Range forms the northernmost drainage divide in North America, separating streams flowing into
4598-644: The Paleozoic , western North America lay underneath a shallow sea, which deposited many kilometers of limestone and dolomite . In the southern Rockies, near present-day Colorado, these ancestral rocks were disturbed by mountain building approximately 300 Ma , during the Pennsylvanian . This mountain-building produced the Ancestral Rocky Mountains. They consisted largely of Precambrian metamorphic rock forced upward through layers of
4719-587: The Pecos River , a tributary of the Rio Grande , in New Mexico. The Rockies vary in width from 110 to 480 kilometres (70 to 300 miles). The Rocky Mountains contain the highest peaks in central North America. The range's highest peak is Mount Elbert in Colorado at 4,401 metres (14,440 feet) above sea level. Mount Robson in British Columbia, at 3,954 m (12,972 ft), is the highest peak in
4840-621: The Permian (when the vast majority of species on Earth were wiped out ). It is unknown why the order Proetida alone survived the Devonian. The Proetida maintained relatively diverse faunas in both deep and shallow water shelf environments throughout the Carboniferous. For many millions of years the Proetida existed untroubled in their ecological niche . An analogy would be today's crinoids , which mostly exist as deep-water species; in
4961-420: The Precambrian this is no longer supported, and it is thought that trilobites originated shortly before they appeared in the fossil record. Very shortly after trilobite fossils appeared in the lower Cambrian, they rapidly diversified into the major orders that typified the Cambrian— Redlichiida , Ptychopariida , Agnostida , and Corynexochida . The first major crisis in the trilobite fossil record occurred in
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5082-741: The Proetida died out. The last trilobites disappeared in the mass extinction at the end of the Permian about 251.9 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had wide diversity and an easily fossilized mineralised exoskeleton , they left an extensive fossil record. The study of their fossils has facilitated important contributions to biostratigraphy , paleontology , evolutionary biology , and plate tectonics . Trilobites are placed within
5203-510: The Sawtooths in central Idaho. The Great Basin and Columbia River Plateau separate these subranges from distinct ranges further to the west. In Canada, the western edge of the Rockies is formed by the huge Rocky Mountain Trench , which runs the length of British Columbia from its beginning as the Kechika Valley on the south bank of the Liard River , to the middle Lake Koocanusa valley in northwestern Montana. The Canadian Rockies are defined by Canadian geographers as everything south of
5324-404: The Selwyn , Mackenzie and Richardson Mountains in Yukon as well as the British Mountains / Brooks Range in Alaska , but those are not officially recognized as part of the Rockies by the Geological Survey of Canada , although the Geological Society of America definition does consider them parts of the Rocky Mountains system as the "Arctic Rockies". The Continental Divide of the Americas
5445-449: The United States Board on Geographic Names in 1925 after Alfred Hulse Brooks , chief USGS geologist for Alaska from 1903 to 1924. Various historical records also referred to the range as the Arctic Mountains, Hooper Mountains, Meade Mountains and Meade River Mountains. The Canadian portion of the range is officially called the British Mountains . Ivvavik National Park is located in Canada's British Mountains. Bob Marshall explored
5566-430: The Wyoming Basin transformed intermountain basins into a relatively flat terrain. The Tetons and other north-central ranges contain folded and faulted rocks of Paleozoic and Mesozoic age draped above cores of Proterozoic and Archean igneous and metamorphic rocks ranging in age from 1.2 billion (e.g., Tetons) to more than 3.3 billion years ( Beartooth Mountains ). There are a wide range of environmental factors in
5687-402: The class Trilobita . Trilobites form one of the earliest known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period ( 521 million years ago ) and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian , all trilobite orders except
5808-406: The labrum in well-preserved trilobite specimens from Cambrian Stage 4 of Morocco, providing new anatomical information regarding the external and internal morphology of trilobites, and the cause of such extraordinary preservation is probably due to their rapid death after an underwater pyroclastic flow. Trilobites saw great diversification over time. For such a long-lasting group of animals, it
5929-401: The oil fields at Prudhoe Bay on Alaska's North Slope . The Alaska Native villages of Anaktuvuk and Arctic Village , as well as the very small communities of Coldfoot , Wiseman , Bettles , and Chandalar , are the range's only settlements. In the far west, near the Wulik River in the De Long Mountains is the Red Dog mine , the largest zinc mine in the world. The range was named by
6050-419: The taxonomy and phylogeny of trilobites. The dorsal surface of the trilobite cephalon (the frontmost tagma , or the 'head') can be divided into two regions—the cranidium and the librigena ("free cheeks"). The cranidium can be further divided into the glabella (the central lobe in the cephalon) and the fixigena ("fixed cheeks"). The facial sutures lie along the anterior edge, at the division between
6171-535: The "Rockies", becoming the first Europeans to report on this uncharted mountain range. Sir Alexander Mackenzie (1764 – March 11, 1820) became the first European to cross the Rocky Mountains in 1793. He found the upper reaches of the Fraser River and reached the Pacific coast of what is now Canada on July 20 of that year, completing the first recorded transcontinental crossing of North America north of Mexico. He arrived at Bella Coola, British Columbia , where he first reached saltwater at South Bentinck Arm, an inlet of
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#17327910423416292-436: The 1970s by Dan Cooper. As a well-known rock collector, he incited scientific and public interest in the location. The fossils are dated to the Givetian (387.2 - 382.7 million years ago) when the Western New York Region was 30 degrees south of the equator and completely covered in water. The site was purchased from Vincent C. Bonerb by the Town of Hamburg with the cooperation of the Hamburg Natural History Society to protect
6413-467: The Ancestral Rocky Mountains. Such sedimentary remnants were often tilted at steep angles along the flanks of the modern range; they are now visible in many places throughout the Rockies, and are shown along the Dakota Hogback , an early Cretaceous sandstone formation running along the eastern flank of the modern Rockies. Just after the Laramide orogeny, the Rockies were like Tibet : a high plateau, probably 6,000 metres (20,000 ft) above sea level. In
6534-408: The Arctic National Wildlife Refuge. The migration path of the Porcupine Caribou herd is the longest of any terrestrial mammal on earth. Because the rocks of the range were formed in an ancient seabed, the Brooks Range contains fossils of marine organisms . In addition to the coral fossils shown, trilobites and brachiopods from the middle Cambrian have been found in the sandy limestones of
6655-496: The Arctic Ocean and the North Pacific. The range roughly delineates the summer position of the Arctic front. It represents the northern extent of the tree line , with little beyond isolated balsam poplar stands occurring north of the continental drainage divide. Trembling aspen and white spruce also occur north of the Brooks Range, though they are limited to sites that have been disturbed by human activity. Southern slopes have some cover of black spruce , Picea mariana , marking
6776-427: The California and Alaska gold rushes combined and was important in the financing of the Union Army during the American Civil War . The transcontinental railroad was completed in 1869, and Yellowstone National Park was established as the world's first national park in 1872. Meanwhile, a transcontinental railroad in Canada was originally promised in 1871. Though political complications pushed its completion to 1885,
6897-402: The Cambrian, trilobites were still active participants in the Ordovician radiation event, with a new fauna taking over from the old Cambrian one. Phacopida and Trinucleioidea are characteristic forms, highly differentiated and diverse, most with uncertain ancestors. The Phacopida and other "new" clades almost certainly had Cambrian forebears, but the fact that they have avoided detection
7018-443: The Central Brooks Range. During the middle of the Cretaceous, the Brooks Range thrust belt underwent significant regional extension. Remains of a woolly mammoth that died about 17,100 years ago were found north of the Brooks Range. A research report on its movement range was published in 2021. While other Alaskan ranges to the south and closer to the coast can receive 250 inches (640 cm) to 500 inches (1,300 cm) of snow,
7139-421: The Middle Cambrian ; surviving orders developed isopygius or macropygius bodies and developed thicker cuticles, allowing better defense against predators (see Thorax below). The end- Cambrian mass extinction event marked a major change in trilobite fauna; almost all Redlichiida (including the Olenelloidea) and most Late Cambrian stocks became extinct. A continuing decrease in Laurentian continental shelf area
7260-430: The Native American cultures. Native American populations were extirpated from most of their historical ranges by disease, warfare, habitat loss (eradication of the bison), and continued assaults on their culture. In 1739, French fur traders Pierre and Paul Mallet, while journeying through the Great Plains, discovered a range of mountains at the headwaters of the Platte River , which local American Indian tribes called
7381-529: The Northern Rockies surrounding Tumbler Ridge, British Columbia . Abandoned mines with their wakes of mine tailings and toxic wastes dot the Rocky Mountain landscape. In one major example, eighty years of zinc mining profoundly polluted the river and bank near Eagle River in north-central Colorado. High concentrations of the metal carried by spring runoff harmed algae , moss , and trout populations. An economic analysis of mining effects at this site revealed declining property values, degraded water quality, and
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#17327910423417502-515: The Olenellina also suggests this suborder to be the ancestral trilobite stock: early protaspid stages have not been found, supposedly because these were not calcified, and this also is supposed to represent the original state. Earlier trilobites may be found and could shed more light on their origins. Three specimens of a trilobite from Morocco, Megistaspis hammondi , dated 478 million years old contain fossilized soft parts. In 2024, researchers discovered soft tissues and other structures including
7623-492: The Pacific Ocean. The Lewis and Clark Expedition (1804–1806) was the first scientific reconnaissance of the Rocky Mountains. Specimens were collected for contemporary botanists, zoologists, and geologists. The expedition was said to have paved the way to (and through) the Rocky Mountains for European-Americans from the East, although Lewis and Clark met at least 11 European-American mountain men during their travels. Mountain men , primarily French, Spanish, and British, roamed
7744-411: The Paleozoic era, vast 'forests' of crinoids lived in shallow near-shore environments. Some of the genera of trilobites during the Carboniferous and Permian periods include: Exactly why the trilobites became extinct is not clear; with repeated extinction events (often followed by apparent recovery) throughout the trilobite fossil record, a combination of causes is likely. After the extinction event at
7865-454: The Plains and the Alpine tundra . The Great Plains lie to the east of the Rockies and is characterized by prairie grasses (below roughly 550 m or 1,800 ft). Alpine tundra occurs in regions above the tree-line for the Rocky Mountains, which varies from 3,700 m (12,000 ft) in New Mexico to 760 m (2,500 ft) at the northern end of the Rockies (near the Yukon). The U.S. Geological Survey defines ten forested zones in
7986-445: The Redlichiida or Corynexochida in the Middle Cambrian. Order Ptychopariida is the most problematic order for trilobite classification. In the 1959 Treatise on Invertebrate Paleontology , what are now members of orders Ptychopariida, Asaphida , Proetida and Harpetida were grouped together as order Ptychopariida; subclass Librostoma was erected in 1990 to encompass all of these orders, based on their shared ancestral character of
8107-423: The Rockies include the La Sal Range along the Utah -Colorado border, the Abajo Mountains and Henry Mountains of Southeastern Utah, the Uinta Range of Utah and Wyoming, and the Teton Range of Wyoming and Idaho. The western edge of the Rockies includes ranges such as the Wasatch near Salt Lake City , the San Juan Mountains of New Mexico and Colorado, the Bitterroots along the Idaho-Montana border, and
8228-464: The Rockies. Zones in more southern, warmer, or drier areas are defined by the presence of pinyon pines / junipers , ponderosa pines , or oaks mixed with pines . In more northern, colder, or wetter areas, zones are defined by Douglas firs , Cascadian species (such as western hemlock ), lodgepole pines / quaking aspens , or firs mixed with spruce . Near tree-line, zones can consist of white pines (such as whitebark pine or bristlecone pine ); or
8349-410: The Rocky Mountains from 1720 to 1800 seeking mineral deposits and furs. The fur-trading North West Company established Rocky Mountain House as a trading post in what is now the Rocky Mountain Foothills of present-day Alberta in 1799, and their business rivals the Hudson's Bay Company established Acton House nearby. These posts served as bases for most European activity in the Canadian Rockies in
8470-485: The Rocky Mountains is one of more rapid change. The Spanish explorer Francisco Vázquez de Coronado —with a group of soldiers and missionaries marched into the Rocky Mountain region from the south in 1540. In 1610, the Spanish founded the city of Santa Fe , the oldest continuous seat of government in the United States, at the foot of the Rockies in present-day New Mexico. The introduction of the horse, metal tools, rifles, new diseases, and different cultures profoundly changed
8591-442: The Rocky Mountains on the Oregon Trail beginning in the 1840s. The Mormons began settling near the Great Salt Lake in 1847. From 1859 to 1864, gold was discovered in Colorado, Idaho, Montana, and British Columbia, sparking several gold rushes bringing thousands of prospectors and miners to explore every mountain and canyon and to create the Rocky Mountains' first major industry. The Idaho gold rush alone produced more gold than
8712-495: The Rocky Mountains. The Rockies range in latitude between the Liard River in British Columbia (at 59° N) and the Rio Grande in New Mexico (at 35° N). Prairie occurs at or below 550 metres (1,800 ft), while the highest peak in the range is Mount Elbert at 4,400 metres (14,440 ft). Precipitation ranges from 250 millimetres (10 in) per year in the southern valleys to 1,500 millimetres (60 in) per year locally in
8833-404: The U.S. portion of the mountain range, apex predators such as grizzly bears and wolf packs had been extirpated from their original ranges, but have partially recovered due to conservation measures and reintroduction . Other recovering species include the bald eagle and the peregrine falcon . Since the last great ice age, the Rocky Mountains were home first to indigenous peoples including
8954-743: The United Kingdom and the United States over the next few decades failed to settle upon a compromise boundary and the Oregon Dispute became important in geopolitical diplomacy between the British Empire and the new American Republic. In 1841, James Sinclair , Chief Factor of the Hudson's Bay Company, guided some 200 settlers from the Red River Colony west to bolster settlement around Fort Vancouver in an attempt to retain
9075-560: The United States, though these rights did not include possession and also included obligations to Britain and Russia concerning their claims in the same region. After 1802, fur traders and explorers ushered in the first widespread American presence in the Rockies south of the 49th parallel. The more famous of these include William Henry Ashley , Jim Bridger , Kit Carson , John Colter , Thomas Fitzpatrick , Andrew Henry , and Jedediah Smith . On July 24, 1832, Benjamin Bonneville led
9196-458: The age of the rocks in which they are found. They were among the first fossils to attract widespread attention, and new species are being discovered every year. In the United States, the best open-to-the-public collection of trilobites is located in Hamburg, New York . The shale quarry, informally known as Penn Dixie, stopped mining in the 1960s. The large amounts of trilobites were discovered in
9317-558: The average snow precipitation on the Brooks Range is reported at 30 inches (76 cm) to 51 inches (130 cm). Due to a changing climate, between the years 1969–2018 the Eastern and Western portions of the Brooks Range have experienced a 17.2% increase in annual precipitation. As measured at the Anaktuvuk Pass weather station (elevation 770 metres (2,530 ft)), the average summer temperatures are 16 °C (61 °F) as
9438-473: The clade Artiopoda , which includes many organisms that are morphologically similar to trilobites, but are largely unmineralised. The relationship of Artiopoda to other arthropods is uncertain. Trilobites evolved into many ecological niches; some moved over the seabed as predators , scavengers , or filter feeders , and some swam, feeding on plankton . Some even crawled onto land. Most lifestyles expected of modern marine arthropods are seen in trilobites, with
9559-428: The coal bed, and separating the gas from the water; or injecting water to fracture the coal to release the gas (so-called hydraulic fracturing ). Agriculture and forestry are major industries. Agriculture includes dryland and irrigated farming and livestock grazing. Livestock are frequently moved between high-elevation summer pastures and low-elevation winter pastures, a practice known as transhumance . Every year
9680-573: The combination of sea level changes and a break in the redox equilibrium (a meteorite impact has also been suggested as a cause). Only a single order, the Proetida , survived into the Carboniferous. Genera of trilobites during the Silurian and Devonian periods include: The Proetida survived for millions of years, continued through the Carboniferous period and lasted until the end of
9801-722: The early 19th century. Among the most notable are the expeditions of David Thompson , who followed the Columbia River to the Pacific Ocean. On his 1811 expedition, he camped at the junction of the Columbia River and the Snake River and erected a pole and notice claiming the area for the United Kingdom and stating the intention of the North West Company to build a fort at the site. By the Anglo-American Convention of 1818 , which established
9922-489: The edge of the North American Plate boundary, far to the west of the Rocky Mountain region. It was not until 80 Ma that these effects began reaching the Rockies. The current Rocky Mountains arose in the Laramide orogeny from between 80 and 55 Ma. For the Canadian Rockies, the mountain building is analogous to pushing a rug on a hardwood floor: the rug bunches up and forms wrinkles (mountains). In Canada,
10043-418: The end of nearly 300 million successful years for the trilobites would not have been unexpected at the time. Trilobites appear to have been primarily marine organisms, since the fossilized remains of trilobites are always found in rocks containing fossils of other salt-water animals such as brachiopods, crinoids, and corals. Some trackways suggest trilobites made at least temporary excursions onto land. Within
10164-610: The end of the Cambrian . Most scientists believe that order Redlichiida , more specifically its suborder Redlichiina , contains a common ancestor of all other orders, with the possible exception of the Agnostina. While many potential phylogenies are found in the literature, most have suborder Redlichiina giving rise to orders Corynexochida and Ptychopariida during the Lower Cambrian, and the Lichida descending from either
10285-467: The end of the Devonian period, what trilobite diversity remained was bottlenecked into the order Proetida. Decreasing diversity of genera limited to shallow-water shelf habitats coupled with a drastic lowering of sea level ( regression ) meant that the final decline of trilobites happened shortly before the end Permian mass extinction event . With so many marine species involved in the Permian extinction,
10406-477: The exoskeleton. Of the 20,000 known species only 38 have fossils with preserved appendages. Trilobites range in length from minute (less than 1 millimetre (0.039 in)) to very large (over 70 centimetres (28 in)), with an average size range of 3–10 cm (1.2–3.9 in). Supposedly the smallest species is Acanthopleurella stipulae with a maximum of 1.5 millimetres (0.059 in). The world's largest-known trilobite specimen, assigned to Isotelus rex
10527-682: The feeding trace, are furrows through the sediment, which are believed to represent the movement of trilobites while deposit feeding. Many of the Diplichnites fossils are believed to be traces made by trilobites walking on the sediment surface. Care must be taken as similar trace fossils are recorded in freshwater and post-Paleozoic deposits, representing non-trilobite origins. Trilobite fossils are found worldwide, with thousands of known species. Because they appeared quickly in geological time, and moulted like other arthropods, trilobites serve as excellent index fossils , enabling geologists to date
10648-577: The first wagon train across the Rocky Mountains by using South Pass in the present State of Wyoming. Similarly, in the wake of Mackenzie's 1793 expedition, fur trading posts were established west of the Northern Rockies in a region of the northern Interior Plateau of British Columbia which came to be known as New Caledonia , beginning with Fort McLeod (today's community of McLeod Lake) and Fort Fraser , but ultimately focused on Stuart Lake Post (today's Fort St. James ). Negotiations between
10769-481: The forty years 1972–2012. Jackson, Wyoming , increased 260%, from 1,244 to 4,472 residents, in those forty years. The rocks in the Rocky Mountains were formed before the mountains were raised by tectonic forces. The oldest rock is Precambrian metamorphic rock that forms the core of the North American continent. There is also Precambrian sedimentary argillite , dating back to 1.7 billion years ago. During
10890-404: The glabella (impendent). Many variations in shape and placement of the hypostome have been described. The size of the glabella and the lateral fringe of the cephalon, together with hypostome variation, have been linked to different lifestyles, diets and specific ecological niches . The anterior and lateral fringe of the cephalon is greatly enlarged in the Harpetida , in other species a bulge in
11011-546: The land from development. In 1994, the quarry became Penn Dixie Fossil Park & Nature Reserve when they received 501(c)3 status and was opened for visitation and collection of trilobite samples. The two most common found samples are Eldredgeops rana and Greenops . A famous location for trilobite fossils in the United Kingdom is Wren's Nest , Dudley , in the West Midlands , where Calymene blumenbachii
11132-400: The last few survivors at the end of the Permian period. Principal evolutionary trends from primitive morphologies, such as exemplified by Eoredlichia , include the origin of new types of eyes, improvement of enrollment and articulation mechanisms, increased size of pygidium (micropygy to isopygy), and development of extreme spinosity in certain groups. Changes also included narrowing of
11253-599: The last sixty million years, erosion stripped away the high rocks, revealing the ancestral rocks beneath, and forming the current landscape of the Rockies. Periods of glaciation occurred from the Pleistocene Epoch (1.8 million – 70,000 years ago) to the Holocene Epoch (fewer than 11,000 years ago). These ice ages left their mark on the Rockies, forming extensive glacial landforms, such as U-shaped valleys and cirques . Recent glacial episodes included
11374-520: The limestone laid down in the shallow sea. The mountains eroded throughout the late Paleozoic and early Mesozoic , leaving extensive deposits of sedimentary rock . Terranes began colliding with the western edge of North America in the Mississippian (approximately 350 million years ago), causing the Antler orogeny . For 270 million years, the focus of the effects of plate collisions were near
11495-535: The loss of recreational opportunities. The analysis also revealed that cleanup of the river could yield $ 2.3 million in additional revenue from recreation. In 1983, the former owner of the zinc mine was sued by the Colorado Attorney General for the $ 4.8 million cleanup costs; five years later, ecological recovery was considerable. The Rocky Mountains contain several sedimentary basins that are rich in coalbed methane . Coalbed methane
11616-439: The marine paleoenvironment, trilobites were found in a broad range from extremely shallow water to very deep water. Trilobites, like brachiopods, crinoids, and corals, are found on all modern continents, and occupied every ancient ocean from which Paleozoic fossils have been collected. The remnants of trilobites can range from the preserved body to pieces of the exoskeleton, which it shed in the process known as ecdysis. In addition,
11737-426: The moult stage and the hardening of the new exoskeleton. A trilobite's cephalon, or head section, is highly variable with a lot of morphological complexity. The glabella forms a dome underneath which sat the "crop" or "stomach". Generally, the exoskeleton has few distinguishing ventral features, but the cephalon often preserves muscle attachment scars and occasionally the hypostome , a small rigid plate comparable to
11858-425: The mountain range, and they are popular tourist destinations, especially for hiking, camping, mountaineering, fishing, hunting, mountain biking, snowmobiling, skiing, and snowboarding. The name of the mountains is a calque of an Algonquian name, specifically Plains Cree ᐊᓯᓃᐘᒋᐩ asinîwaciy (originally transcribed as-sin-wati ), literally "rocky mountain / alp". The first mention of their present name by
11979-643: The mountain range. After explorations of the range by Europeans, such as Sir Alexander Mackenzie , and Anglo-Americans, such as the Lewis and Clark Expedition , natural resources such as minerals and fur drove the initial economic exploitation of the mountains, although the range itself never experienced a dense population. Most of the highest summits of the Rocky Mountains are in Colorado , with that state having an average elevation in excess of 2,000 metres (6,600 ft). Public parks and forest lands protect much of
12100-555: The mountains are home to Dall sheep , grizzly bears , black bear , gray wolf , moose and porcupine caribou . In Alaska, the Western Arctic Caribou herd (490,000 strong in 2004) traverses the Brooks Range in its annual migration. The smaller Central Arctic herd (32,000 in 2002), as well as the 123,000 animal Porcupine Caribou herd, likewise migrate through the Brooks range on their annual journeys in and out of
12221-450: The normal 300 to 500 kilometres (200 to 300 mi). Scientists hypothesize that the shallow angle of the subducting plate increased the friction and other interactions with the thick continental mass above it. Tremendous thrusts piled sheets of crust on top of each other, building the broad, high Rocky Mountain range. The current southern Rockies were forced upwards through the layers of Pennsylvanian and Permian sedimentary remnants of
12342-406: The northern limit of those trees. As the global mean temperature increases, tree line has been observed to move further north, changing the boundaries of where these trees are found. An increase in shrub abundance is also being experienced in areas which were previously dominated by tundra, impacting the ecology of the area. As one of the most remote and least-disturbed wildernesses of North America,
12463-654: The northern peaks. Average January temperatures can range from −7 °C (20 °F) in Prince George, British Columbia, to 6 °C (43 °F) in Trinidad, Colorado . Therefore, there is no single monolithic ecosystem for the entire Rocky Mountain Range. Instead, ecologists divide the Rockies into a number of biotic zones . Each zone is defined by whether it can support trees and the presence of one or more indicator species . Two zones that do not support trees are
12584-617: The northernmost part of Western Canada , to New Mexico in the Southwestern United States . Depending on differing definitions between Canada and the U.S., its northern terminus is located either in northern British Columbia 's Terminal Range south of the Liard River and east of the Trench , or in the northeastern foothills of the Brooks Range / British Mountains that face the Beaufort Sea coasts between
12705-547: The plains in fall and winter for bison and to the mountains in spring and summer for fish, deer, elk, roots, and berries. In Colorado, along with the crest of the Continental Divide, rock walls that Native Americans built for driving game date back 5,400–5,800 years. A growing body of scientific evidence indicates that indigenous people had significant effects on mammal populations by hunting and on vegetation patterns through deliberate burning. Recent human history of
12826-404: The possible exception of parasitism (where scientific debate continues). Some trilobites (particularly the family Olenidae ) are even thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived food. The largest trilobites were more than 70 centimetres (28 in) long and may have weighed as much as 4.5 kilograms (9.9 lb). Trilobites belong to
12947-417: The pre-glabellar area is preserved that suggests a brood pouch. Highly complex compound eyes are another obvious feature of the cephalon. Facial or cephalic sutures are the natural fracture lines in the cephalon of trilobites. Their function was to assist the trilobite in shedding its old exoskeleton during ecdysis (or molting). All species assigned to the suborder Olenellina , that became extinct at
13068-405: The rate of speciation during the period known as the Cambrian explosion because they are the most diverse group of metazoans known from the fossil record of the early Cambrian. Trilobites are excellent stratigraphic markers of the Cambrian period: researchers who find trilobites with alimentary prosopon, and a micropygium, have found Early Cambrian strata. Most of the Cambrian stratigraphy
13189-695: The scenic areas of the Rocky Mountains draw millions of tourists. The main language of the Rocky Mountains is English. But there are also linguistic pockets of Spanish and indigenous languages. People from all over the world visit the sites to hike, camp, or engage in mountain sports . In the summer season, examples of tourist attractions are: In the United States: In Canada, the mountain range contains these national parks : Glacier National Park in Montana and Waterton Lakes National Park in Alberta border each other and are collectively known as Waterton-Glacier International Peace Park . In
13310-494: The service industries that support them. Tents and camps became ranches and farms, forts and train stations became towns, and some towns became cities. Economic resources of the Rocky Mountains are varied and abundant. Minerals found in the Rocky Mountains include significant deposits of copper, gold, lead, molybdenum , silver, tungsten , and zinc . The Wyoming Basin and several smaller areas contain significant reserves of coal, natural gas, oil shale , and petroleum. For example,
13431-655: The terranes and subduction are the foot pushing the rug, the ancestral rocks are the rug, and the Canadian Shield in the middle of the continent is the hardwood floor. Further south, an unusual subduction may have caused the growth of the Rocky Mountains in the United States, where the Farallon Plate dove at a shallow angle below the North American Plate . This low angle moved the focus of melting and mountain building much farther inland than
13552-594: The thoracic furrows, is also a common evolutionary trend. Notable examples of this were the orders Agnostida and Asaphida , and the suborder Illaenina of the Corynexochida . Effacement is believed to be an indication of either a burrowing lifestyle or a pelagic one. Effacement poses a problem for taxonomists since the loss of details (particularly of the glabella ) can make the determination of phylogenetic relationships difficult. Although it has historically been suggested that trilobites originated during
13673-406: The thorax and increasing or decreasing numbers of thoracic segments. Specific changes to the cephalon are also noted; variable glabella size and shape, position of eyes and facial sutures, and hypostome specialization. Several morphologies appeared independently within different major taxa (e.g. eye reduction or miniaturization). Effacement, the loss of surface detail in the cephalon, pygidium, or
13794-505: The tracks left behind by trilobites living on the sea floor are often preserved as trace fossils . There are three main forms of trace fossils associated with trilobites: Rusophycus , Cruziana and Diplichnites —such trace fossils represent the preserved life activity of trilobites active upon the sea floor. Rusophycus , the resting trace, are trilobite excavations involving little or no forward movement and ethological interpretations suggest resting, protection and hunting. Cruziana ,
13915-596: The trilobites unscathed; some distinctive and previously successful forms such as the Telephinidae and Agnostida became extinct. The Ordovician marks the last great diversification period amongst the trilobites: very few entirely new patterns of organisation arose post-Ordovician. Later evolution in trilobites was largely a matter of variations upon the Ordovician themes. By the Ordovician mass extinction , vigorous trilobite radiation has stopped, and gradual decline
14036-448: The ventral plate in other arthropods. A toothless mouth and stomach sat upon the hypostome with the mouth facing backward at the rear edge of the hypostome. Hypostome morphology is highly variable; sometimes supported by an un-mineralised membrane (natant), sometimes fused onto the anterior doublure with an outline very similar to the glabella above (conterminant) or fused to the anterior doublure with an outline significantly different from
14157-554: The very end of the Early Cambrian (like Fallotaspis , Nevadia , Judomia , and Olenellus ) lacked facial sutures. They are believed to have never developed facial sutures, having pre-dated their evolution. Because of this (along with other primitive characteristics), they are thought to be the earliest ancestors of later trilobites. Some other later trilobites also lost facial sutures secondarily. The type of sutures found in different species are used extensively in
14278-930: The winter, skiing is the main attraction, with dozens of Rocky Mountain ski areas and resorts . The adjacent Columbia Mountains in British Columbia contain major resorts such as Panorama and Kicking Horse , as well as Mount Revelstoke National Park and Glacier National Park. There are numerous provincial parks in the British Columbia Rockies, the largest and most notable being Mount Assiniboine Provincial Park , Mount Robson Provincial Park , Northern Rocky Mountains Provincial Park , Kwadacha Wilderness Provincial Park , Stone Mountain Provincial Park and Muncho Lake Provincial Park . Trilobite Trilobites ( / ˈ t r aɪ l ə ˌ b aɪ t s , ˈ t r ɪ l ə -/ ; meaning "three lobes") are extinct marine arthropods that form
14399-619: The years 1969–2018. In certain areas of the Brooks Range, year round snow cover or "perennial snowfields", can be found. In 1985, 34 square miles of snowfields were recorded, where as that number has dropped to under four square miles in 2017. Rocky Mountains The Rocky Mountains , also known as the Rockies , are a major mountain range and the largest mountain system in North America . The Rocky Mountains stretch 3,000 miles (4,800 kilometers) in straight-line distance from
14520-520: Was fundamental in formulating and testing punctuated equilibrium as a mechanism of evolution. Identification of the 'Atlantic' and 'Pacific' trilobite faunas in North America and Europe implied the closure of the Iapetus Ocean (producing the Iapetus suture), thus providing important supporting evidence for the theory of continental drift . Trilobites have been important in estimating
14641-469: Was proposed to be elevated out of the asaphid superfamily Trinucleioidea . Sometimes the Nektaspida are considered trilobites, but these lack a calcified exoskeleton and eyes. Some scholars have proposed that the order Agnostida is polyphyletic, with the suborder Agnostina representing non-trilobite arthropods unrelated to the suborder Eodiscina . Under this hypothesis, Eodiscina would be elevated to
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