[permalink] [id link]
The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian periods respectively.
from
Wikipedia
Some Related Sentences
Ordovician and named
A. Öpik named a new genus of orthide brachiopod from the Ordovician period of earth history Sampo.
Since Alfred Eisenack first recognised and named the group in 1930, the Chitinozoa have proven incredibly useful as a stratigraphic markers in biostratigraphy during the Ordovician, Silurian and Devonian periods.
After much dispute, the next two periods of the Paleozoic era, the Ordovician and Silurian, were named after pre-Roman Celtic tribes from Wales, the Ordovices and Silures.
In the Ordovician Period, a land mass, which has been named Gondwana ( present day South America, Africa, Antarctica and Australia ), straddled the space between the South Pole and the Equator on one side of the globe.
The overthrust in New York which places Lower Cambrian rocks in contact with Middle Ordovician rocks is named for him, known as Emmons ' line, formerly Logan's line.
Ordovician and after
The connection between grazer and stromatolite abundance is well documented in the younger Ordovician evolutionary radiation ; stromatolite abundance also increased after the end-Ordovician and end-Permian extinctions decimated marine animals, falling back to earlier levels as marine animals recovered.
An intervening period occurred in the Mid Ordovician ( about 450 Ma ) when a sheet of quartz-rich sand blanketed a large part of the continent after the above-mentioned units were laid down.
In late Devonian and in the Carboniferous the archipelago Armorica of southern Europe, which had rifted off Gondwana after Avalonia later in the Ordovician, was pushed into Avalonia, creating a second range, the North American / European Variscan, to the east of the Caledonide / Appalachian.
Ordovician and Ordovices
The Ordovician geologic period was first described by Charles Lapworth in 1879 based on rocks located in the original lands of the Ordovices.
Ordovician and was
Despite the long recognition of its distinction from younger Ordovician rocks and older Precambrian rocks, it was not until 1994 that this time period was internationally ratified.
While recognition of the distinct Ordovician Period was slow in the United Kingdom, other areas of the world accepted it quickly.
Life continued to flourish during the Ordovician as it did in the Cambrian, although the end of the period was marked by a significant mass extinction.
The Ordovician and Silurian periods were warm greenhouse periods, with the highest sea levels of the Paleozoic ( 200 m above today's ); the warm climate was interrupted only by a ~ 30 Ma cool period, the Early Palaeozoic Icehouse, culminating in the Hirnantian glaciation.
Even the leading Snowball proponent Hoffman agrees that the ~ million year long Gaskiers glaciation did not lead to global glaciation, although it was probably as intense as the late Ordovician glaciation.
It is not clear when the transition to a terrestrial existence was made, but it is considered plausible that it took place between the Ordovician and late Silurian — approximately — via the intertidal zone.
The late Ordovician species of trilobite that spent some of its life in the plankton layer near the ocean surface was much harder hit than deep-water dwellers, which tended to stay put within quite restricted areas.
Charles Lapworth ( 20 September 1842 – 13 March 1920 ) was an English geologist who pioneered faunal analysis using index fossils and identified the Ordovician period.
The Delamerian Fold Belt is mainly composed of Neoproterozoic-Cambrian rocks and was deformed in the Late Cambrian Delamerian Orogeny whereas the Lachlan Fold Belt contains mainly Cambrian-Devonian rocks with the main deformations occurring in the late Ordovician to early Carboniferous interval.
Production was found in the Ordovician Wilcox Sand at depths of ~ 6000 ' with initial production rates as high as.
During the Early Ordovician there was a great increase in the diversity of bivalve species and the dysodont, heterodont and taxodont dentitions evolved.
During the Ordovician and Silurian periods ( 500-410 million years ago ), Hạ Long Bay was deep sea.
During the Ordovician period the collision of Laurentia, Gondwanaland, and Avalonia, referred to as the Taconic Orogeny, caused the formation to fold, thrust, and uplift above sea level, where later layers were eroded away and the schist was exposed.
One is called the Ordovician Bioerosion Revolution ( see Wilson & Palmer, 2006 ) and the other was in the Jurassic.
The Ordovician – Silurian extinction event, or quite commonly the Ordovician extinction, was the second-largest of the five major extinction events in Earth's history in terms of percentage of genera that went extinct and second largest overall in the overall loss of life.
Through the Late Ordovician outgassing from major volcanism was balanced by heavy weathering of the uplifting Appalachian Mountains, which sequestered CO < sub > 2 </ sub >.
The limestone formed during the Ordovician Period approximately 450 to 500 million years ago, but it was formed at the bottom of a relatively shallow ocean that then covered what is today Rockingham County, Virginia.
Much of the collecting was done in the second half of the 19th century and notable among the collections are the David Homfray collection from the Cambrian and Ordovician strata of Wales ; and the collections of George H. Hickling and D. M. S. Watson which are from the Silurian of the Dudley district, West Midlands and from the Old Red Sandstone.
According to legend Carreg Bica ( Bica's rock ), a large sea-weathered stack of Ordovician rock on the beach, is the tooth of the giant Bica who lived in the Ceredigion area, and was forced to spit his tooth onto the beach following a bad toothache.
During the Ordovician Period, about 450 million years ago, the North American continent was situated along the equator, and a warm shallow sea covered much of Minnesota.
This sand was first deposited as beach sand, probably eroded from earlier Cambrian sandstones, along the shores of the Ordovician sea.
Ordovician and by
The Cambrian is the first geological period of the Paleozoic Era, lasting from million years ago ( mya ) ; it is succeeded by the Ordovician.
The Cambrian period follows the Ediacaran and is followed by the Ordovician period.
The star-shaped holes ( Catellocaula vallata ) in this Upper Ordovician bryozoan represent a soft-bodied organism preserved by bioimmuration in the bryozoan skeleton.
In the Cambrian, their global distribution shows no sign of provinciality, suggesting a long-lived planktonic larval life stage ; but by the Ordovician distinct assemblages were becoming evident.
He is best known for pioneering faunal analysis of Silurian beds by means of index fossils, especially graptolites, and his proposal ( eventually adopted ) that the beds between the Cambrian beds of north Wales and the Silurian beds of South Wales should be assigned to a new geological period: the Ordovician.
Downpatrick is characterised by the rolling drumlins that are a feature of the Lecale area and a legacy of glaciation during the Pleistocene, the Down drumlins themselves are underlaid by Ordovician and Silurian shales and grits.
The low knobs or " benches " on the northwest side of Tussey Mountain and the southeast side of Evitts Mountain are formed by the Ordovician Bald Eagle Formation, another sandstone, that is stratigraphically below the Tuscarora.
The low knobs or " benches " on the northwest side of Tussey Mountain and the southeast side of Evitts Mountain are formed by the Ordovician Bald Eagle Formation, another sandstone, that is stratigraphically below the Tuscarora.
The specific formation beneath Palmyra is an Ordovician Epler Formation, characterized by a high number of surface depressions and sinkholes.
The uplifted, nearly circular Adirondack Mountains consist of a core of ancient Precambrian rocks that are surrounded by upturned Cambrian and Ordovician sedimentary rocks.
The first armored agnathans — the Ostracoderms, precursors to the bony fish and hence to the tetrapods ( including humans )— are known from the middle Ordovician, and by the Late Silurian the agnathans had reached the high point of their evolution.
Most of the highest ground is formed by the masses of granite which have been intruded into the Ordovician and Silurian rocks ; the Criffel mass lies about Dalbeattie and Bengairn, another mass extends east and west between the Cairnsmore of Fleet and Loch Ken, another lies northwest and southeast between Loch Doon and Loch Dee and a small mass forms the Cairnsmore of Carsphairn.
Hiatus concretion encrusted by bryozoans ( thin, branching forms ) and an edrioasteroid ; Kope Formation ( Upper Ordovician ), northern Kentucky.
The star-shaped holes ( Catellocaula vallata ) in this Upper Ordovician bryozoan represent a tunicate preserved by Fossil | bioimmuration in the bryozoa n skeleton.
The Bluegrass region is characterized by underlying fossiliferous limestone, dolostone, and shale of the Ordovician geological age.
Layers of sediment continued to form slates and shales along the ocean floor mixed with volcanic rock pushed up as Iapetus began to shrink by the process of subduction during the Ordovician period ( 488-443 million years ago ).
500 million years ago, in the Ordovician period, southern Britain, the east coast of North America and south-east Newfoundland broke away from Gondwana to form the continent of Avalonia, which by 440 Ma had drifted ( by the mechanisms of plate tectonics ) to about 30 ° south.
In the Ordovician geological period the first known cephalopods swam by a natural built-in reciprocating hydrojet.
0.266 seconds.