Cenozoic Earth History Notes

Cenozoic Overview

  • Divided into three main periods:

    • Paleogene

    • Neogene

    • Quaternary

  • Well-represented geologically with abundant fossils

  • Rocks have not been largely altered since deposition

  • Cenozoic spans approximately 63.5 million years

Geological Timeline

  • Precambrian: ~3,000,000,000 years

  • Paleozoic: ~290,000,000 years

  • Mesozoic: ~185,000,000 years

  • Cenozoic: ~63,500,000 years

  • Quaternary: 2,600,000 years

Cenozoic Rocks in North America

  • Significant exposures of sedimentary and igneous rocks

  • Provide insights on continental environments and past shallow seas

Plate Tectonics

  • Breakup of Pangea led to modern continental configuration

  • North and South America moved westward, widening Atlantic Ocean

  • San Andreas Fault formed due to motion over East Pacific Rise

Orogenic Belts

  • Major orogenic activity occurs in:

    • Circum-Pacific (Ring of Fire)

    • Alpine–Himalayan

Alpine Orogeny

  • Greater mountain-building activities between Spain and Turkey

  • Caused by collision of African and Eurasian plates

Himalayan Orogeny

  • India moved north from Gondwana, colliding with Eurasia

  • Resulted in crustal thickening and uplift of the Himalayas

Circum-Pacific Orogenic Belt

  • Includes North, Central, South America; Eastern Asia; New Zealand

  • Characterized by volcanism and seismic activity

Andes Mountains

  • Formed from South American plate colliding with oceanic lithosphere

  • Associated with volcanic activity and crustal thickening

North American Cordillera

  • Complex mountainous area from Rocky Mountains to Pacific

  • Significant geological evolution began in Neoproterozoic

Laramide Orogeny

  • Late Cretaceous-Eocene deformation associated with the Farallon plate subduction

  • Characterized by vertical uplifts rather than typical tectonic folding

  • Renewed igneous activity occurred after disruption of the oceanic plate

Types of Faults

  • Normal fault: extension

  • Thrust fault: compression

  • Reverse fault

  • Strike-slip fault: shear

Deformation Characteristics

  • In Montana, Lewis thrust fault showcases interaction between ancient and younger rock formations

  • Erosion features further isolate geological structures in the region