A number of regional terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected a formal international system of subdivisions. There exist Baltoscandic, British, Siberian, North American, … See more

During the Ordovician, the southern continents were assembled into Gondwana, which reached from north of the equator to the South Pole. The Panthalassic Ocean, centered in the northern hemisphere, covered ov… See more

The Ordovician was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic … See more

The Early Ordovician climate was very hot, with intense greenhouse conditions and sea surface temperatures comparable to those during the Early Eocene Climatic Optimum. Carbon dioxide levels were very high at the Ordovician … See more

For most of the Late Ordovician life continued to flourish, but at and near the end of the period there were mass-extinction events that seriously affected conodonts and planktonic forms like graptolites. … See more