Ordovizium und Silur. Überschwemmungen,eine Eiszeit und die Eroberung des Festlandes

Ordovician and Silurian sediments are predominantly black shales formed from anoxic pelagic environments. Adjacent shallow marine areas are represented by reefs and well‐sorted sands deposited worldwide on continental shelves. Pelagic realms hosted a great variety of graptolite colonies which due to their rapid evolution are excellent index fossils besides a multitude of new species of trilobites and brachiopods. Reef builders were mainly bryozoans and tabulate corals. During the Ordovician, the earliest spores mark the beginning conquest of land by plants. A mass extinction at the end of the Ordovician was probably caused by a worldwide climatic change which is also evident from traces of a contemporaneous glaciation.