Misplaced Pages

#583416

48-592: Eighty million years ago the Billings metro area was the shore of the Western Interior Seaway , a sea that went from the present-day Gulf of Mexico to the Arctic North. Sediment and sand from the sea were deposited around the shoreline. Over time the sea rose and fell leaving behind a deep layer of sand. Over millions of years this sand was compressed into the sandstone the rims are made of. It

96-1101: A drop in sea level rise from Antarctic glaciation, brought an end to the Tethys as it previously existed, fragmenting it into the Indian Ocean, the Mediterranean Sea, and the Paratethys . It was preceded by the Paleo-Tethys Ocean , which lasted between the Cambrian and the Early Triassic , while the Neotethys formed during the Late Triassic and lasted in some form up to the Oligocene – Miocene boundary (about 24–21 million years ago) when it completely closed. A portion known as

144-744: A pearly luster. Tethys Ocean The Tethys Ocean ( / ˈ t iː θ ɪ s , ˈ t ɛ -/ TEETH -iss, TETH - ; Greek : Τηθύς Tēthús ), also called the Tethys Sea or the Neo-Tethys , was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era . It was the predecessor to the modern Indian Ocean , the Mediterranean Sea , and the Eurasian inland marine basins (primarily represented today by

192-583: A petition campaign to preserve the Rims in their natural state. When the group's effort's failed, the Billings Gazette published an editorial suggesting that the area be preserved as a national monument. The National Park Service considered the idea, but concluded that the Rimrocks were "of less than national significance." Western Interior Seaway The Western Interior Seaway (also called

240-455: A remnant of the older Paleo-Tethys Ocean . The Western Tethys was not simply a single open ocean. It covered many small plates, Cretaceous island arcs , and microcontinents . Many small oceanic basins ( Valais Ocean , Piemont-Liguria Ocean , Meliata Ocean ) were separated from each other by continental terranes on the Alboran , Iberian , and Apulian plates. The high sea level in

288-413: Is Monument Rocks , an exposed chalk formation towering 70 feet (21 m) over the surrounding range land. The Western Interior Seaway is believed to have behaved similarly to a giant estuary in terms of water mass transport. Riverine inputs exited the seaway as coastal jets, while correspondingly drawing in water from the Tethys in the south and Boreal waters from the north. During the late Cretaceous,

336-690: Is known as Eagle Sandstone . Around a million years ago a much larger river than the current-day Yellowstone River began cutting a canyon into the valley floor of Eagle Sandstone, creating what today is known as the Rimrocks. The river still continues to cut into the valley floor. This can be witnessed at the base of the Sacrifice Cliff and the Northern Edge of Briarwood Mountain in the South Hills. The Rimrock's first Caucasian inhabitants were French traders that temporarily resided in

384-587: Is what is thought to have allowed for upwelling in the Arabian Sea and led to the establishment of the modern South Asian Monsoon . It also caused major modifications to the functioning of the AMOC and ACC . During the Oligocene (33.9 to 23 Mya), large parts of central and eastern Europe were covered by a northern branch of the Tethys Ocean, called the Paratethys . The Paratethys was separated from

432-527: The Arctic Ocean . The two land masses it created were Laramidia to the west and Appalachia to the east. At its largest extent, it was 2,500 feet (760 m) deep, 600 miles (970 km) wide and over 2,000 miles (3,200 km) long. By the late Cretaceous, Eurasia and the Americas had separated along the south Atlantic, and subduction on the west coast of the Americas had commenced, resulting in

480-633: The Black Sea and Caspian Sea ). During the early Mesozoic, as Pangaea broke up, the Tethys Ocean was defined as the ocean located between the ancient continents of Gondwana and Laurasia . After the opening of the Indian and Atlantic oceans during the Cretaceous Period and the breakup of these continents over the same period, it came to be defined as the ocean bordered by the continents of Africa, Eurasia, India, and Australasia. During

528-735: The Cretaceous Seaway , the Niobraran Sea , the North American Inland Sea , the Western Interior Sea and sometimes nicknamed "Hell's Aquarium" ) was a large inland sea that split the continent of North America into two landmasses for 34 million years. The ancient sea, which existed from the early Late Cretaceous (100 Ma ) to the earliest Paleocene (66 Ma), connected the Gulf of Mexico to

SECTION 10

#1732772833584

576-518: The Laramide orogeny , the early phase of growth of the modern Rocky Mountains . The Western Interior Seaway may be seen as a downwarping of the continental crust ahead of the growing Laramide/Rockies mountain chain. The earliest phase of the seaway began in the mid-Cretaceous when an arm of the Arctic Ocean transgressed south over western North America; this formed the Mowry Sea, so named for

624-583: The Mowry Shale , an organic-rich rock formation . In the south, the Gulf of Mexico was originally an extension of the Tethys Ocean . In time, the southern embayment merged with the Mowry Sea in the late Cretaceous, forming a completed seaway, creating isolated environments for land animals and plants. Relative sea levels fell multiple times , as a margin of land temporarily rose above the water along

672-512: The Oceanid sea nymphs and of the world's great rivers, lakes and fountains. The eastern part of the Tethys Ocean is sometimes referred to as Eastern Tethys. The western part of the Tethys Ocean is called Tethys Sea, Western Tethys Ocean, or Paratethys or Alpine Tethys Ocean. The Black , Caspian , and Aral seas are thought to be its crustal remains, though the Black Sea may, in fact, be

720-513: The Paratethys when the Alpine front was still 100 km (62 mi) farther south. In 1885, the Austrian palaeontologist Melchior Neumayr deduced the existence of the Tethys Ocean from Mesozoic marine sediments and their distribution, calling his concept Zentrales Mittelmeer ( lit.   ' Central Mediterranean Sea ' ) and described it as a Jurassic seaway, which extended from

768-588: The Triassic , a new ocean began forming in the southern end of the Paleo-Tethys Ocean. A rift formed along the northern continental shelf of Southern Pangaea (Gondwana). Over the next 60 million years, that piece of shelf, known as Cimmeria , traveled north, pushing the floor of the Paleo-Tethys Ocean under the eastern end of northern Pangaea (early / proto- Laurasia ). The Neo-Tethys Ocean formed between Cimmeria and Gondwana, directly over where

816-490: The 1960s, "fixist" geologists, however, regarded Tethys as a composite trough, which evolved through a series of orogenic cycles. They used the terms 'Paleotethys', 'Mesotethys', and 'Neotethys' for the Caledonian , Variscan , and Alpine orogenies, respectively. In the 1970s and 1980s, these terms and 'Proto-Tethys', were used in different senses by various authors, but the concept of a single ocean wedging into Pangea from

864-873: The Aralo-Caspian Formation extending from close to the Danube delta across Crimea, up the east side of the Volga river to Samara, then south of the Urals to beyond the Aral Sea. Brackish and upper freshwater components (OSM) of the Miocene are now known to extend through the North Alpine foreland basin and onto the Swabian Jura with thickness of up to 250 m (820 ft); these were deposited in

912-750: The Caribbean to the Himalayas. In 1893, the Austrian geologist Eduard Suess proposed the hypothesis that an ancient and extinct inland sea had once existed between Laurasia and the continents which formed Gondwana II. He named it the Tethys Sea after the Greek sea goddess Tethys. He provided evidence for his theory using fossil records from the Alps and Africa. He proposed the concept of Tethys in his four-volume work Das Antlitz der Erde ( The Face of

960-739: The Dakotas and retreated south towards the Gulf of Mexico . This shrunken and final regressive phase is sometimes called the Pierre Seaway . During the early Paleocene , parts of the Western Interior Seaway still occupied areas of the Mississippi Embayment , submerging the site of present-day Memphis . Later transgression, however, was associated with the Cenozoic Tejas sequence , rather than with

1008-477: The Earth ). In the following decades during the 20th century, " mobilist " geologists such as Uhlig (1911), Diener (1925), and Daque (1926) regarded Tethys as a large trough between two supercontinents which lasted from the late Palaeozoic until continental fragments derived from Gondwana obliterated it. After World War II , Tethys was described as a triangular ocean with a wide eastern end. From 1920s to

SECTION 20

#1732772833584

1056-683: The Indian Ocean). The Turgai Strait extended out of the Peri-Tethys, connecting the Tethys with the Arctic Ocean . As theories have improved, scientists have extended the "Tethys" name to refer to three similar oceans that preceded it, separating the continental terranes: in Asia, the Paleo-Tethys (Devonian–Triassic), Meso-Tethys (late Early Permian –Late Cretaceous), and Ceno-Tethys (Late-Triassic–Cenozoic) are recognized. None of

1104-751: The Mesozoic flooded most of these continental domains, forming shallow seas. During the early Cenozoic, the Tethys Ocean could be divided into three sections: the Mediterranean Tethys (the direct predecessor to the Mediterranean Sea), the Peri-Tethys (a vast inland sea that covered much of eastern Europe and central Asia, and the direct predecessor to the Paratethys Sea), and the Indian Tethys (the direct predecessor to

1152-605: The Paleo-Tethys formerly rested. During the Jurassic period about 150 Mya, Cimmeria finally collided with Laurasia and stalled, so the ocean floor behind it buckled under , forming the Tethys Trench . Water levels rose, and the western Tethys shallowly covered significant portions of Europe, forming the first Tethys Sea. Around the same time, Laurasia and Gondwana began drifting apart , opening an extension of

1200-659: The Paratethys was isolated during the Oligocene (34 million years ago) and lasted up to the Pliocene (about 5 million years ago), when it largely dried out. The modern inland seas of Europe and Western Asia, namely the Black Sea and Caspian Sea, are remnants of the Paratethys Sea. The sea is named after Tethys , who, in ancient Greek mythology, is a water goddess, a sister and consort of Oceanus , mother of

1248-576: The Shiloh, West End, Central-Terry, Downtown Core and North Park sections of the city. The East Rims border the eastern edge of the Downtown core, the South Hills and Briarwood sections of the city. Much of the Heights and Lockwood sit on top of the first rise of the Rimrocks. A second rise borders the eastern edge of Lockwood and also runs several miles north of the city and borders northeast sections of

1296-636: The Tethys Sea between them which today is the part of the Atlantic Ocean between the Mediterranean and the Caribbean . As North and South America were still attached to the rest of Laurasia and Gondwana, respectively, the Tethys Ocean in its widest extension was part of a continuous oceanic belt running around the Earth between about latitude 30°N and the Equator . Thus, ocean currents at

1344-710: The Tethys oceans should be confused with the Rheic Ocean , which existed to the west of them in the Silurian Period. To the north of the Tethys, the then-land mass is called Angaraland and to the south of it, it is called Gondwanaland . From the Ediacaran (600  Mya ) into the Devonian (360 Mya ), the Proto-Tethys Ocean existed and was situated between Baltica and Laurentia to

1392-601: The Tethys were eventually closed off in what is now the Middle East during the Miocene , as a consequence of the northern migration of Africa/Arabia and global sea levels falling due to the concurrent formation of the Antarctic Ice Sheet . This decoupling occurred in two steps, first around 20 Mya and another around 14 Mya. The complete closure of the Tethys led to a global reorganization of currents, and

1440-417: The Tethys with the formation of the Alps, Carpathians , Dinarides , Taurus , and Elburz mountains during the Alpine orogeny . During the late Miocene , the Paratethys gradually disappeared, and became an isolated inland sea. Separation from the wider Tethys during the early Miocene initially led to a boost in primary productivity for the Paratethys, but this gave way to a total ecosystem collapse during

1488-461: The Western Interior Seaway went through multiple periods of anoxia , when the bottom water was devoid of oxygen and the water column was stratified. At the end of the Cretaceous, continued Laramide uplift hoisted the sandbanks (sandstone) and muddy brackish lagoons (shale), thick sequences of silt and sandstone still seen today as the Laramie Formation , while low-lying basins between them gradually subsided. The Western Interior Seaway divided across

Rimrocks - Misplaced Pages Continue

1536-650: The ancestral Transcontinental Arch , each time rejoining the separated, divergent land populations, allowing a temporary mixing of newer species before again separating the populations. At its largest, the Western Interior Seaway stretched from the Rockies east to the Appalachian Mountains , some 1,000 km (620 mi) wide. At its deepest, it may have been only 800 or 900 metres (2,600 or 3,000 ft) deep, shallow in terms of seas. Two great continental watersheds drained into it from east and west, diluting its waters and bringing resources in eroded silt that formed shifting delta systems along its low-lying coasts. There

1584-479: The city. The second rise is over 600 feet in places making the total from the valley floor to the top of the second rise over 1,400 feet in places. The tallest single section of the Rimrocks starts at the eastern border of the downtown area with a cliff known as Sacrifice Cliff and extends to the south for roughly 18 miles. This area is known as Coburn Hill . In the late 1960s, the Concerned Citizens Olivia Reifenberger and Brooke Wirkkala with Better Billings organized

1632-414: The crevasses of the sandstone during the harsh winter of 1832. Veterans of the Napoleonic Wars , William Beshoar and Alexander Coumou were accompanied by Swedish and German businessmen Collin Holmberg and Andrew Strub. In the early 1940s a journal along with remnants of the group were discovered partially buried within the crevasses by geologists Kai Glidden and Kyler Bennett. The North Rims border north of

1680-409: The early-mid Cenozoic, the Indian, African, Australian and Arabian plates moved north and collided with the Eurasian plate, which created new borders to the ocean, a land barrier to the flow of currents between the Indian and Mediterranean basins, and the orogenies of the Alpide belt (including the Alps , Himalayas , Zagros , and Caucasus Mountains ). All of these geological events, in addition to

1728-412: The flightless Hesperornis that had stout legs for swimming through water and tiny wings used for marine steering rather than flight; and the tern-like Ichthyornis , an early avian with a toothy beak. Ichthyornis shared the sky with large pterosaurs such as Nyctosaurus and Pteranodon . Pteranodon fossils are very common; it was probably a major participant in the surface ecosystem, though it

1776-411: The historic æra, a vast region of Europe and Asia was covered by a Mediterranean Sea of brackish water, of which the present Caspian is the diminished type. ... To render the distinction between these accumulations and all others clear and unambiguous, we have adopted the term Aralo-Caspian, first applied in a geographical sense, by our great precursor Humboldt, to this region of the globe. ... Judging from

1824-412: The late Miocene as a result of rapid dissolution of carbonate . In Chapter 13 of his 1845 book, Roderick Murchison described a distinctive formation extending from the Black Sea to the Aral Sea in which the creatures differed from those of the purely marine period that preceded them. The Miocene deposits of Crimea and Taman (south of the Sea of Azov ) are identical with formations surrounding

1872-406: The masses of water now separated from each other, from the Aral to the Black Sea inclusive, were formerly united in this vast pre-historical Mediterranean ; which (even if we restrict its limits to the boundaries we already know, and do not extend them eastward, amid low regions untrodden by geologists) must have exceeded in size the present Mediterranean! On the accompanying map, Murchison shows

1920-399: The massive 4-to-5-metre (13 to 16 ft) long Xiphactinus , larger than any modern bony fish . Other sea life included invertebrates such as mollusks , ammonites , squid-like belemnites , and plankton including coccolithophores that secreted the chalky platelets that give the Cretaceous its name, foraminiferans and radiolarians . The seaway was home to early birds, including

1968-403: The north and Gondwana to the south. From the Silurian (440 Mya ) through the Jurassic periods, the Paleo-Tethys Ocean existed between the Hunic terranes and Gondwana. Over a period of 400 million years, continental terranes intermittently separated from Gondwana in the Southern Hemisphere to migrate northward to form Asia in the Northern Hemisphere. About 250 Mya, during

Rimrocks - Misplaced Pages Continue

2016-434: The present Caspian Sea , in which the univalves of freshwater origin are associated with forms of Cardiacae and Mytili that are common to partially saline or brackish waters. This distinctive fauna has been found throughout all the enormously developed Tertiary formations of the southern and south-eastern steppes. ... and leads at once to the conviction, that during long periods antecedent, as will be hereafter explained, to

2064-484: The previous event responsible for the seaway. The Western Interior Seaway was a shallow sea, filled with abundant marine life. Interior seaway denizens included predatory marine reptiles such as plesiosaurs , and mosasaurs . Other marine life included sharks such as Squalicorax , Cretoxyrhina , and the giant shellfish-eating Ptychodus mortoni (believed to be 10 metres (33 ft) long); and advanced bony fish including Pachyrhizodus , Enchodus , and

2112-422: The recital of travellers and from specimens of the rock, we have no doubt that it extended to Khivah and the Aral Sea ; beyond which the low level of the adjacent eastern deserts would lead us to infer, that it spread over wide tracts in Asia now inhabited by the Turkomans and Kirghis , and was bounded only by the mountains of the Hindoo Kusk and Chinese Tartary . ... there can be no sort of doubt, that all

2160-403: The seaway. Many species can easily fit in the palm of the hand, while some like Inoceramus (Haploscapha) grandis could be well over a meter in diameter. Entire schools of fish sometimes sought shelter within the shell of the giant Platyceramus . The shells of the genus are known for being composed of prismatic calcitic crystals that grew perpendicular to the surface, and fossils often retain

2208-422: The time around the Early Cretaceous ran very differently from the way they do today. Between the Jurassic and the Late Cretaceous , which started about 100 Mya, Gondwana began breaking up, pushing Africa and India north across the Tethys and opening up the Indian Ocean. Throughout the Cenozoic (66 million to the dawn of the Neogene, 23 Mya), the connections between the Atlantic and Indian Oceans across

2256-430: Was found in only the southern reaches of the seaway. Inoceramids (oyster-like bivalve molluscs) were well-adapted to life in the oxygen-poor bottom mud of the seaway. These left abundant fossils in the Kiowa , Greenhorn , Niobrara , Mancos , and Pierre formations. There is great variety in the shells and the many distinct species have been dated and can be used to identify specific beds in those rock formations of

2304-495: Was little sedimentation on the eastern shores of the seaway; the western boundary, however, consisted of a thick clastic wedge eroded eastward from the Sevier orogenic belt . The western shore was thus highly variable, depending on variations in sea level and sediment supply. Widespread carbonate deposition suggests that the seaway was warm and tropical, with abundant calcareous planktonic algae . Remnants of these deposits are found in northwest Kansas. A prominent example

#583416