1. The Earth has had three distinct atmospheres over its life to date. Describe the

       composition of these atmospheres and when they occurred.

           2.The same process responsible for the relatively young average age of rocks on the Earth is also responsible for the fact that we have so few craters. Names this process and describe how it works.

3.   What is the source of the magnetic field that we have on Earth?

 4.Describe two of the most rare/unique physical features of Venus and their cause.

 5.What are the main indicators that there was once a liquid surface water on Mars?

       Describe and locate any current forms of water on Mars?