Continental Red Beds

•      Obviously continental red beds refers

  –   to red rocks on the continents,

  –   but more specifically it means red sandstone or shale

  –   colored by
  iron oxides,

  –   especially
  hematite
  (Fe[2]O[3])

























•      Life may have developed from nonliving materials as early as 3.9 billion years ago





                                         Small Shelly Fauna















     Tillites and

glacial features

on all continents

except Antarctica

900 to 600 m.y.

ago, not contin-

uous, but 4

episodes.

Greatest extent in

Earth history, with

some in apparent

near- equitorial

areas.













                                      Model for origin of BIF

•      Oxygen-rich upper ocean

•      Oxygen-poor deep ocean

•      Upwelling brings Fe and Si-rich water up

•      Precipitation occurs































































                                             Next step:

•      1.4 Ga multicellular algae (?) Montana





•      The evolutionary links between unicellular and multicellular organisms were probably colonial
protists

                               Diversification of Multicellular Algae

•      Early Multicellular EK

•      Allowed for larger size and cell specialization

•      Oldest multicellular organism (Fig 4.9)

  –   Red Algea about 1.0 Ga

                                  Cambrian-Precambrian Transition