OBJECTIVE: Describe the formation of the solid Earth. INTRO: – What do you think the Earth looked like the first billion years of its existence?

Formation of the Earth Effects of Gravity & Heat Formed within 10 million years of the collapse of the solar nebula Grew from the collision of planetismals Collisions generated heat – Melted rock – Volcanoes and Earthquakes release the heat trapped within

Formation of the Earth Layers of the Earth Crust – Made of rocks and materials low in density Mantle – Made of materials that are denser than the crust Core – Made of nickel and iron which is the densest

Formation of the Earth Formation of Earth’s Atmosphere Early Atmosphere – Earth was HOT and had large amounts of poisonous gases, carbon dioxide and water vapor Changing Atmosphere – As Earth cooled, the water vapor condensed to create the first oceans

Formation of the Earth Role of Life First life forms in the ocean Bacteria are the first life-forms to develop They were simple (unicellular) and did not need oxygen

Formation of the Earth Source of Oxygen Organisms that first began to do photosynthesis began to create an oxygen-rich atmosphere – Photosynthesis: Uses light to convert carbon dioxide to oxygen Over the next billions of years, Earth’s atmosphere filled up with oxygen

Formation of the Earth Formation of Oceans & Continents Oceans – After a few million years, Earth was cool enough for it to rain – Water began to cover the Earth and create the first oceans Continents – Heavier denser materials sank into the Earth – Lighter rocks and materials piled up to create our continents

Formation of the Earth Why Life is on Earth Liquid water – Earth is not too hot or cold to freeze or vaporize water Gravity – Holds us down, but helps create an atmosphere Gases – Photosynthesis and respiration help cycle carbon dioxide and oxygen Magnetic Field – Blocks harmful radiation

OBJECTIVE: Describe the formation of solid Earth. OUTRO: – Why did the Earth separate into distinct layers?