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					| Origin of the Earth |  
					| Lecture 13 3/11/98
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					| |  | Today we start into our review of the history of Life that will occupy the remainder of the course. | 
 |  | We will look at the origins of the earth and its features that may have made it suitable for life. | 
 |  | Earth and the Solar System formed at the same time approximately 4.6 Billion Years ago. | 
 |  | The earth's size and possition made it suitable for life to develop. | 
 |  | Life probably originated around 3.8 billion years ago. | 
 | The origins of the Universe | 
 | The origins of the Solar System | 
 |  | coelessing of cold matter into proto-sun and proto-planets | 
 |  | melting and differentiation | 
 |  | Volcanic activity generated a new atmosphere of H20, CO2, methane, N2 | 
 |  | Earths position relative to the sun allowed water to condense to form the oceans. | 
 |  | Earth's size ensured that volcanic activity could continue to the present | 
 
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