[ Main ] Educator's Guide
Outreach Initiatives
[ Site Map ]
Geology | Lehigh River Watershed Explorations | Weather | Environmental Issues | Data Collection Activities
 
The Geologic Time Scale - Ordovician

 

ERA

PERIOD

AGE
(of start)

Cenozoic

Quaternary

1.6 my

Tertiary

65 my

Mesozoic

Cretaceous

140 my

Jurassic

205 my

Triassic

250 my

Paleozoic

Permian

290 my

Carboniferous

355 my

Devonian

410 my

Silurian

438 my

Ordovician

510 my

Cambrian

540 my

Ordovician 510 - 438 million years ago

Life

Dominant life includes:
Molluscs, Bryozoa, Graptolite, Brachiopods, Conodonts (early vertebrates)

The first vertebrates and primitive fish evolve during this time period.

Climate

During the early- middle Ordovician, the climate was relatively warm and moist.

During the late Ordovician, Gondwana positioned itself over the South Pole, resulting in massive glaciers and a drop in sea level. A mass extinction event occurred at the end of the Ordovician, killing about 60% of marine genera.

Geology

Supercontinent over South Pole in late Ordovician called Gondwana.

The main rock types/ deposits in PA are limestone, dolomite, and shale.

Geologic Time Scale
Ordovician
 
Geologic Time Scale | What is Geology? | Exploringthe Lehigh Valley | Rock on! Educational Material

Pennsylvania Geology | Which Way is North? | Geologic Explorations | Dino Inquiry | Wonderful World of Rocks and Minerals


LEO EnviroSci Inquiry is brought to you by the Lehigh Environmental Initiative at Lehigh University.
Copyright ©2000-2011 Lehigh Environmental Initiative at Lehigh University. All rights reserved.