- Conventionally, the Cambrian, Ordovician, and Silurian systems constitute the Lower Palaeozoic and the Devonian, Carboniferous, and Permian comprise the Upper Palaeozoic.
- These are overlain by low-grade metamorphosed sediments and volcanics of Ordovician and Silurian age.
- The so-called ophiolitic relics at the Moldanubian-Brunovistulian boundary show Early Ordovician to Silurian crystallization ages.
The Silurian lasted from about 439 to 409 million years ago. The first true fish and land plants appeared, and the end of the period is marked by the climax of the Caledonian orogeny
early 18th century: from Latin Silures (denoting a people of ancient SE Wales) + -ian.
Definition of Silurian in:
- The US English dictionary