Chap. 9

  1. The Proterozoic Eon is divided into 3 eras:
    • 1.) Paleoproterozoic Era
    • 2.) Mesoproterozoic Era
    • 3.) Neoproterozoic Era
  2. Beginning of the Proterozoic marks the beginning of:
    More modern style of plate tectonics & sedimentation; More modern global climate w/ glaciations; Establishment of beginnings of oxygen-rich atmosphere; Emergence of eukaryotes
  3. Major events of the Paleoproterozoic:
    Active plate tectonics & mountain building; Earth's first glaciation; Rise in atmospheric oxygen; Accumulation of high concentrations of organic matter in sediments
  4. Evidence for glaciation includes: Varves
    mudstones w/ alternating summer and winter layers of sediment
  5. Evidence for glaciation includes: Glacial dropstones
    Dropped from melting icebergs in varved sedimentary rocks
  6. Evidence for glaciation includes: Striation on beds
    due to abrasion as ice moved
  7. Extensive banded iron formations on the western shores of Lake Superior indicated that:
    photosynthesis was occurring and oxygen was being produced
  8. Highlights of the Mesoproterozoic (1.6 to 1 billion years)
    Assembly of supercontinent Rodinia (1.1 billion years ago)
  9. Rifting in Rodinia:
    Began to rift and break up about 750 million years ago– forming the proto-Pacific Ocean
  10. Highlights of the Neoproterozoic
    Snowball Earth– extensive continental glaciations
  11. Photosynthetic microorganisms
  12. Unicellular and heterotrophic (i.e. eat othersfor energy), Protist (i.e. eukaryotic microorganisms), Foraminifera, amoeba
  13. Multicellular animals (eukaryotes)
  14. Life at the beginning of the Proterozoic was similar to that in the Archean:
    Anaerobic prokaryotes in oxygen-deficient environments; Photosynthetic cyanobacteria constructed stromatolites
  15. The appearance of eukaryotes is a major event in the history of life.
    Have potential for sexual reproduction (increases variation through genetic recombination); appeared by Archean, but diversified during Proterozoic
  16. Appeared in Neoproterozoic about 630 mil years ago; Preserved as impressions of soft-bodied organisms in sandstones
    Metazoans- or multicellular animals (eukaryotes); ex: jellyfish, coral
  17. Fossils with hard parts or shells appeared in the ______ Era
Card Set
Chap. 9
geo test