Humboldt State University ® Department of Chemistry

Richard A. Paselk

	Evolution and Christianity
Spring 2008	Notes	Office: SA560a
Office Hours: T 1000-1150, W 1600-1650, Th 1000-1050, F 1400-1450 other times by appointment		Phone: x 5719 Home: 822-1116
		e-mail: rap1@humboldt.edu

Deep Time and The History of the Earth - 2

Overview of Earth History

Time line of early Earth: from origin of solar system (4.57 Ga) to present (5 meter model).

Major occurrences of Precambrian (approx. 90% of Earth history):

• 4.57 Ba
  Formation of Solar System
  Oldest known meteorites.
  • 4.47 Ba
    Earth's accretion complete.
  • 4.4 Ba
    Jack Hills
    Zircons of apparent continental origin ­ evidence of early (Hadean) crust and surface water
• 4.0 Ba
  Hadean-Archean Boundary: Archean eon begins.
  Oldest known rocks.
  • 3.96 Ba
    Acasta Gneiss
    Oldest known rock.
  • 3.9 Ba
    End of intense bombardment.
  • 3.5 Ba
    Warrawonna Group
    Banded iron & black chert containing stromatolites & filamentous structures
  • 3.2 Ba
    Deep-sea volcanic rock
    Filamentous "fossils."
  • 3.0 Ba
    Fig Tree Group
    Banded iron & black chert containing stromatolites & dividing cells; high ¹²C/¹³C, pristane and phytane.
  • 2.7 Ba
    Steranes, a eucaryotic chemical marker, appear.
• 2.5 Ba
  Archean-Proterozoic Boundary: Proterozoic eon begins
  Extensive global metamorphism, modern tectonic geology begins? Large, extensive stromatolitic reefs, oxygenic photosynthesis well established.
  • 2.2 Ba
    First extensive glaciation in geological record.
  • 2.2-2.0 Ba
    Oxygen increases, 0.0001-0.1 atm.
  • 2.1 Ba
    Gunflint Chert
    Stromatolites, black cherts & chemical fossils. Dramatically increased diversity vs. earlier sites.
  • 2.0 Ba
    Banded iron formations cease.
  • 2.0-1.8 Ba
    Earliest fossil eucaryotes (Green algae?). Distinguished by larger cell size (<10um vs >100um)
  • 1.75 Ba
    Assured eucaryote algae-acritarchs
  • 1.25 Ba
    Oldest known metaphyte (green & brown algae) fossils. Ornamented acritarchs.
  • 1.0 Ba
    First fossils of branched algae ("seaweed").
  • 0.8-0.75 Ba
    Bitter Springs
    Diverse assemblage with cyanobacteria, bacteria and green algae. Some cells in meiotic? Tetrads, possible organelles. Black chert, stromatolites, high ¹²C/¹³C, pristane and phytane.
  • 0.65 Ba
    Ediacaran megabiota
    First fossils of large multicellular organisms other than algae.
  • 0.6 Ba
    "Snowball Earth"
    Extensive glaciation in tropics, most of ocean covered with sea-ice. Oxygen increases to near modern level.
• 0.542 Ba
  Phanerozoic Eon begins with the Cambrian.
  Trace fossils of Phycodes pedum and small shelly organisms mark end of Precambrian.

Phanerozoic time ­ HSU NHM exhibits website

© R A Paselk

Last modified 17 January 2008