Monday, January 4th, 2016 Materials: Pencil Notebook Computer Agenda: Pre- Cambrian Era Notes DO: Today we will Learn about Earth history starting with the pre-Cambrian era. DQ: What do you think Earth was like during the Pre-Cambrian Era? How long ago do you think this was?

Earth History Review Pangea – Connecting time eras in Earth’s history.

Go to X Students7th Grade  7C- Merritt Class period Earth History COPY the “Earth History Notes” document to your H drive. Open & Start Editing ** You will be typing notes with this document for the next two weeks!

Precambrian Age 4.6bya-500mya Eon: a unit of time equal to a billion years. Subdivided into eras Era: a long and distinct period of history with a particular feature or characteristic. Subdivided into periods. Period: Identified by distinct features/characteristics. May also be subdivided into epochs and ages. The Hadean Eon 4.6-3.8 billion years ago (bya) The Archean Eon 3.8-2.5 bya The Proterozoic Eon 2.5 bya-542 mya

(Hadean)Formation of the Earth Planets form Gaseous Jupiter forms first Collisions form inner metallic planets Icy asteroids deliver water

The Hadean Eon Solar System forms Solar nebula collapses due to gravity Proto-sun forms from hydrogen gas and begins hydrogen fusion Dust particles condense, and clump

Formation of Earth’s Crust The Moon was formed between Earth and a smaller planet occupying the same orbit Dense iron magma sinks to core Lighter silica magma rises to form magma ocean Magma cools and forms crust Oldest surviving continental crust 3.8 bya Acasta Gneiss, Canada

Late Heavy Bombardment from Space Asteroid belt is disrupted by migration of the outer icy planets Zircon grains found that are 4.3bya in metamorphic and sedimentary rock, confirming a modern rock cycle was in operation Formation of oceans and atmosphere Video – Formation of Pre-Cambrian Era https://www.youtube.com/watch?v=8ZqZ0UoHPjc

The Archaen Eon Crust cools & Plate tectonics is established Atmosphere composed of nitrogen, hydrogen, carbon, but very little oxygen The first life appears and forming the earliest fossils Complex chemical reactions change carbon molecules into earliest life forms First photosynthetic organisms produce oxygen

Proterozoic Eon Protero= first Zoon= life in Greek First multicellular animals by end of interval Larger land masses form from the accretion of smaller ones 4 major mountain-building episodes Continents begin to erode into oceans creating marine environments where life could diversify Increasing oxygen in the atmosphere caused some life forms to go extinct, while allowing others to flourish Oldest known glaciers