Definition & Meaning | English word ORDOVICIAN

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Definitions of ORDOVICIAN

1. (geology) Of a geologic period within the Paleozoic era; comprises lower, middle and upper epochs from about 488 to 443 million years ago.
2. (geology) The Ordovician period.

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Examples of Using ORDOVICIAN in a Sentence

• The Ordovician, named after the Welsh 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 North Wales in the Cambrian and Silurian systems, respectively.
• Some geological timescales divide the Paleozoic informally into early and late sub-eras: the Early Paleozoic consisting of the Cambrian, Ordovician and Silurian; the Late Paleozoic consisting of the Devonian, Carboniferous and Permian.
• Machaeridia is an extinct group of armoured, segmented annelid worms, known from the Early Ordovician (Late Tremadoc) to Carboniferous.
• Charles Lapworth FRS FGS (20 September 1842 – 13 March 1920) was a headteacher and an English geologist who pioneered faunal analysis using index fossils and identified the Ordovician period.
• Galena Group, a sedimentary sequence of Ordovician limestone that was deposited atop the Decorah Shale.
• Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian.
• The county lies over 16 different rock formations (which are from the Ordovician, Silurian, and Devonian) and 51 different soils.
• As a result, bedrock found in the area now bounded as Boone County is almost entirely Ordovician, as opposed to nearby counties like McHenry and Carroll which contain large areas of later Silurian bedrock.
• Most of Mt Imlay National Park was formed during the Ordovician Period, 500 to 435 million years ago, from sedimentary and metamorphosed rocks of the Mallacoota Beds, part of the Southern Highlands Fold Belt, including greywacke, sandstone and shale.
• The Healdton Field, encompassing Healdton and located in the western portion of Carter County, produces from the Pennsylvanian Healdton sands of the Hoxbar Group and the Ordovician massive carbonate Arbuckle Group.
• The stone collected in Panton is from the Ordovician Crown Point Formation, therefore it is common to find fossils of invertebrates preserved in objects made from Panton Stone.
• The park's rock formations, made famous by Robert Stevens and Harold Williams, include oceanic crust and mantle rock exposed by the obduction process of plate tectonics, as well as sedimentary rock formed during the Ordovician, Precambrian granite and Palaeozoic igneous rocks.
• The rocks that form Snowdon were produced by volcanoes in the Ordovician period, and the massif has been extensively sculpted by glaciation, forming the pyramidal peak of Snowdon and the arêtes of Crib Goch and Y Lliwedd.
• The earliest known fossil vertebrates were heavily armored fish discovered in rocks from the Ordovician period about 485 to 444 Ma (megaannum, million years ago), with jawed vertebrates emerging in the following Silurian period (444 to 419 Ma) with the placoderms and acanthodians.
• Fossil denticles (tooth-like scales in the skin) resembling those of today's chondrichthyans date at least as far back as the Ordovician, with the oldest unambiguous fossils of cartilaginous fish dating from the middle Devonian.
• Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Ordovician Soom Shale, the Silurian Waukesha Biota, the Devonian Hunsrück Slates and Gogo Formation, the Carboniferous Mazon Creek, the Triassic Madygen Formation, the Jurassic Posidonia Shale and Solnhofen Limestone, the Cretaceous Yixian, Santana, & Agua Nueva formations and the Tanis Fossil Site, the Eocene Fur Formation, Green River Formation, Messel Formation & Monte Bolca, the Miocene Foulden Maar and Ashfall Fossil Beds, the Pliocene Gray Fossil Site, and the Pleistocene Naracoorte Caves & La Brea Tar Pits.
• The Bluegrass region is characterized by underlying fossiliferous limestone, dolomite, and shale of the Ordovician geological age.
• This extinction pulse is typically attributed to the Late Ordovician glaciation, which abruptly expanded over Gondwana at the beginning of the Hirnantian and shifted the Earth from a greenhouse to icehouse climate.
• The Lammermuir Hills are formed from a succession of Silurian and Ordovician age marine sediments known as greywackes together with siltstones, shales and mudstones.
• Below the approximately 200 metre thick glacial derived sediments of the moraine lies thick bedrock successions of Precambrian rocks and up to 200 metres of Ordovician aged rock (see geology below), capped by a regional unconformity of erosion and non-deposition to the Quaternary period.
• The softer Ordovician rocks that underlie the lake have eroded away, and the stronger Silurian rocks stand as a ridge that formed the lake basin.
• In areas near the Boysen Fault, just north of Boysen Reservoir's dam at the southern mouth of Wind River Canyon, erosion has removed the upper part of the thrust of the mountain, exposing Cambrian and Ordovician rocks, overlaying Triassic age rocks.
• is dated to the Middle-Upper Ordovician, while Panderodus and Ozarkodina were discovered in Rhuddanian, Lower Silurian period.
• In 1879 the pioneering English geologist Charles Lapworth named the Ordovician geological period after the Ordovices because the rocks he was studying were found in the tribe's former territories in North Wales.
• The entire Silurian section below the Liston Creek limestone and a few feet of the upper Ordovician probably would be visible in the vicinity of La Fontaine.

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