1. Why are the rocks significant despite their appearance?

2. What effects did the comet or asteroid have on the earth?

3. What "radical" theory did a few scientists have?

4. How did the Alvarezes deduce that a huge asteroid had struck the earth?

5. For what purpose were the breccia taken from the earth?

6. What information did Penfield's magnetometer uncover? What does this information suggest?

7. What effect of asteroid impact was discovered in the 1960s?

8. What effect would an asteroid have on the world today?