Paleozoic

Early Paleozoic Earth History

  • William Smith (1815): Published first geologic map of England, illustrating over 20 years of work, showing relationship between rocks, orogenic episodes, and sea level changes linked to plate tectonics and glaciation.

  • Paleozoic Periods: First five Paleozoic periods described and named based on British rocks by Smith; notably, Carboniferous coal beds essential for powering the Industrial Revolution.

Geological Time Scale

  • Eons and Eras:

    • Phanerozoic Eon: Contains Paleozoic, Mesozoic, and Cenozoic eras.

    • Major Events:

    • Cambrian to Late Ordovician: Earliest land plants and first fish.

    • Carboniferous: Formation of coal beds.

  • Ordovician Glaciation: Documented movements of Gondwana; tillites found in North Africa.

Paleozoic Paleogeography

  • Reconstruction Methods: Utilizes paleoclimates, paleomagnetics, fossils, and stratigraphy.

  • Late Cambrian to Late Ordovician: Coverage by shallow seas; marked geological formations such as Taconic Highlands from orogeny events.

Continental Architecture

  • Supercontinent Pannotia: Began breaking up around 550 million years ago, forming six major continents (e.g., Baltica, Gondwana).

  • North America: Characterized by four major mobile belts from mountain-building episodes and cratonic sequences marking transgressions/regressions.

Sequence Stratigraphy

  • Definition: Study of rock sequences guided by time-stratigraphic frameworks, focusing on facies and unconformities.

  • Usage: Important in the petroleum industry for correlation and mapping purposes.

  • The Sauk Sequence: First major transgression onto North America, with records of marine sediments and extensive carbonate deposits.

Paleogeography of the Grand Canyon

  • Cambrian Rock Formation: Displays transgression characteristics; Vertical successions indicate migration of offshore facies over time.

  • Time-Transgressive Facies: Cambrian formations show varying ages across different locations.

Ordovician Paleogeography of North America

  • Sauk Sea Regression: Resulted in extensive erosion and significant unconformities marking the transition to the Tippecanoe sequence.

  • Equator Shift: Noted during counterclockwise rotation of North America during the Ordovician period.