Arenig
（重定向自Arenigian）
![Arenig Fawr, the mountain which lends its name to the geological series](/Images/godic/202412/21/Arenig_Fawr_w1542.JPG")
![Asaphus](/Images/godic/202412/21/Naturhistorisches_Museum_Vienna_Dez_2006_0731542.jpg")
![Colpocoryphe grandis](/Images/godic/202412/21/Colpocoryphe_grandis.3_-_Fosil1542.JPG")
- For the mountains in Wales, see Arenigs.
In geology, the Arenigian (or 'Arenig') refers both to a time interval during the Lower Ordovician period and also to the suite of rocks which were deposited during this interval.