*Most geological information about the Precambrian is derived from Cratons, the large portions of continents
that have not undergone substantial tectonic deformation since early Paleozoic time.
Precambrian Shield- large Precambrian portion of a Craton that is exposed at Earth's surface.
Redshift- increase in the wavelength of lightwaves travelling through space, evidence that the universe is
Supernova- exploding star that casts off matter of low density. How our sun was formed.
Protocontinents- numerous felsic bodies of rock that emerged duringArchean time formed small continents.
Terrane- is a geologically distinctive region of Earth's crust that has behaved as a coherent crustal block.
Greenstone Belts- long stratified rock bodies that sit in masses of high grade metamorphic rocks of felsic
*Life appeared on Earth after 4.5 billion years ago.
Mantle differentiated enough to form small cratons (continental crust)
Plate Tectonics began to operate
Small cratons coalesced into larger cratons
Oceans formed due to Volcanic emission of water vapour which condensed
Dissolved salts from weathering of exposed rocks and ocean crust
Modern salinity reached
Archean fossils appear to only represent prokaryotes, these primitive lifeforms diversified rapidly, known to
have existed 3.5 billion years ago.
Stromatolites suggest that photosynthesis was occurring onArchean seafloors 3.5 billion years ago.
Eukaryotic Cells- cells that contain chromosomes and nuclei.