During the Early Ordovician there was a great increase in the diversity of bivalve species and the dysodont, heterodont and taxodont dentitions evolved.

It has been conjectured that a hypernova may have caused the Ordovician – Silurian mass extinction on Earth 440 million years ago, but there is no categorical evidence for this hypothesis.

The crater is filled with sediments, between Pleistocene sediments and crushed rapakivi granite bedrock there is a layer of Paleozoic ( Ordovician ) limestones.

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.

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.

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 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 Ordovician geologic period was first described by Charles Lapworth in 1879 based on rocks located in the original lands of the Ordovices.

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.

Although corals first appeared in the Cambrian period, some, fossils are extremely rare until the Ordovician period, 100 million years later, when rugose and tabulate corals became widespread.

A major current ( 2004 – 08 ) project of UNESCO's International Geoscience Programme ( IGCP ), following a successful probe of the Ordovician biodiversification, has as its major objective to seek the possible physical and chemical causes, related to changes in climate, sea level, volcanism, plate movements and extraterrestrial influences, of the Ordovician biodiversification, this end-Ordovician extinction, and the ensuing Silurian radiation.

In the Ordovician period much volcanism deposited a range of minerals and rocks over the north western parts of Gwynedd whilst to the east of the River Conwy lies a large area of upland rolling hills underlain by the Silurian mudstones and grits comprising the Denbigh and Migneint Moors.

Category: Ordovician volcanism

However, as if to offset this trend, Gondwana moved south with considerable speed, so that, in Ordovician time, most of West Gondwana ( Africa and South America ) lay directly over the South Pole.

Evidence for the existence of sharks dates from the Ordovician period, over 450 – 420 million years ago, before land vertebrates existed and before many plants had colonized the continents.

During the Ordovician and Silurian periods, the genus Dalmanites was widespread all over the world, inhabiting a variety of climates and sea conditions.

The Queenston Delta is a 300-mile-wide clastic wedge of sediment deposited over what is now eastern North America during the late Ordovician period due to the erosion of mountains created during the Taconic orogeny.

Rockhouse strata is over 440 million years old ( Upper Ordovician Period, Cumberland Formation, Silty Dolomite ).

In the Early Ordovician epoch ( about 480 million years ago ) the microcontinent ( a small fragment of continental lithosphere ) Avalonia ( at present lithosphere that is scattered over the east of New England, the south of Newfoundland, parts of New Brunswick and Nova Scotia, southern Ireland, most of England and Wales, the low countries and northern Germany ) began to separate from the northern margin of Gondwana.

Beginning in the Ordovician Period, mountain building intermittently proceeded in the eastern part of the Appalachian region throughout the rest of the era, bringing in new sediments.

in height, runs along the western edge of the Ordovician formations and divides the region into an eastern and a western area, known respectively to physiographers as the Salem Plateau and the Springfield Plateau.

One of the oldest formations in the region, it dates back to the Ordovician period ( between 488. 3 ± 1. 7 to 443. 7 ± 1. 5 million years ago ), is composed of schist and graywacke deposits.

The Bluegrass region is characterized by underlying fossiliferous limestone, dolostone, and shale of the Ordovician geological age.

Underlying bedrock of the region is chiefly Mississippian limestone, chert, shale, and sandstone with exposures of Devonian, Silurian, Ordovician, and Cambrian limestone, chert, and shale .< ref name =" Arch ">

This line is found in the Middle Ordovician Asery Level deposits of the Volkhov River region near Saint Petersburg, Russia.

The fossils of this species are found only in the middle Ordovician deposits of the Volkhov River region near Saint Petersburg, Russia.

Geology of Ordovician rocks, Melville Peninsula and region, southeastern district of Franklin.

A virtual underwater observatory shows the Hudson ’ s Bay region during the Ordovician period.