Lower Ordovician

The earliest epoch of the Ordovician period of geologic time, extending from about 490- to 460,000,000 years ago.

Related terms:

• Middle Ordovician
• Lower Cretaceous
• Lower Devonian
• Lower Jurassic
• Lower Triassic
• Lower Permian
• Lower Silurian
• Lower Pennsylvanian
• Lower Mississippian
• Lower Cambrian