1. Define the term 'fossil' and explain how fossils form. 2. What is the fossil record? What does it show us? 3 (a) List the four eons of the Earth’s history. (b) Outline how these eons relate to the Cambrian and Precambrian eras. (c) Outline the significance of Precambrian fossils. 4. Diagrams 1–4 are rock strata from four different locations. (a) Place the four locations in a sequence from those containing the oldest rocks to those containing the youngest rocks. (b) List each of the fossils (in all locations) in order of age from oldest to youngest. You may use the diagrams and a flow diagram if you wish. 5. Explain why there is more difficulty in obtaining fossils from ancient rocks than those in rocks that are only a few hundred million years old? 6. The fossil record indicates that some fossil species have disappeared. Account for this disapperance of species in the fossil record.