The major ice caps in the late Ordovician lay between base of N. extraordinarius biozone and lower part persculptus biozone, consistent with low values CIA, CIW PIA for Huadi No. 1 well, reflecting a short-lived cold dry climate from top Wufeng-Guanyinqiao Formation to Longmaxi well. These observations provide geochemical record evidence Gondwana glaciation at end South China.

The earliest Osprioneides kampto borings were found in bryozoan colonies of Sandbian age from northern Estonia (Baltica). The Ordovician was a time of great increase in the quantities of hard substrate removed by single trace makers. Increased predation pressure was most likely the driving force behind the infaunalization of larger invertebrates such as the Osprioneides trace makers in the Ordo...

Beecher's Trilobite Bed in the Frankfort Shale of New York State preserves an exceptional record of the benthic macrofauna of a Late Ordovician deepwater marine environment. It has long been famous for specimens of the trilobites Triarthrus eatoni (Hall), Cryptolithus bellulus (Ulrich), Primaspis crosotus (Locke), and Cornuproetus beecheri (Ruedemann), new combination, which preserve the ventra...

Gamma-ray bursts (hereafter GRB) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth experienced mass extinctions that eliminated...

—In post-Cambrian time, five events—the end-Ordovician, end-Frasnian in the Late Devonian, end-Permian, end-Triassic, and end-Cretaceous—are commonly grouped as the ‘‘big five’’ global intervals of mass extinction. Plotted by magnitude, extinction intensities for all Phanerozoic substages show a continuous distribution, with the five traditionally recognized mass extinctions located in the uppe...

Michigan's first commercial oil field was discovered at Port Huron, St. Clair County, in 1886. By 1910, 21 shallow wells had been completed in the Dundee formation at depths of about 500 to 650 feet. In 1910 the daily production from this field amounted to about 10 barrels of oil per day, all of which was used locally in the manufacture of lubricants. However, it was not until 1925 when the Sag...

Magnetostratigraphic studies of the Ordovician provide evidence for nature core-mantle boundary interactions, and means dating correlation across differing environmental regimes. We new magnetostratigraphic data from Middle Upper Ordovician, compiling this into a polarity chronostratigraphic scale Dapingian to Hirnantian interval. The are derived Backside Beck Cheney Longville sections in Brita...