Summary of Early Paleozoic Earth History

Early Paleozoic Earth History

Introduction

  • 1815: William Smith published first geological map of England.

  • Rocks record geological changes due to plate tectonics and glaciation.

  • Smith mapped coal mines, contributing to descriptions of Paleozoic periods.

Paleozoic Eras and Major Events

  • Cambrian (488-542 Ma): First fish and land plants.

  • Ordovician (444-488 Ma): First reptiles; glaciations in Gondwana.

  • Silurian (416-444 Ma): First amphibians; coral and sponge reefs became abundant.

  • Devonian (359-416 Ma): Age of fishes; extensive barrier reef formation.

  • Carboniferous (299-359 Ma): Major coal swamps; significant mountain-building.

Paleozoic Paleogeography

  • Reconstruction through paleoclimates, paleomagnetics, fossils, etc.

  • Major continental movements shaped early Paleozoic landscapes.

  • Late Cambrian: Epeiric seas; passive continental margins dominate.

Pangea Formation

  • By end of Permian (251 Ma); changes in ocean and atmosphere circulation patterns.

Continental Developments

  • Cratons and mobile belts characterized the early Paleozoic architecture.

  • Cratonic sequences: Major transgressive-regressive cycles due to tectonics/glaciation.

Paleozoic Mineral Resources

  • Important resources: coal, oil, limestone, gypsum; influenced industrial development.

Climatic and Geological Changes

  • Late Paleozoic glacial cycles affected Gondwana; coal deposits formed.

  • Major orogenic events shaped modern landscapes and climates.

Evolution of North America

  • Dynamic sedimentary record during periods of mountain-building and marine transgressions.

  • Orogenies: Taconic, Acadian, and Alleghenian.

  • Significant black shale and coal formations mark various periods.

Cyclothem Deposition

  • Cyclothems represent alternating marine and nonmarine sedimentation; indicate sea level changes.

  • Characterized by coal deposits under marine shales.

End of Paleozoic

  • Transition marked by Pangaea formation and the largest mass extinction event affecting marine and terrestrial life.