The following diagram represents three rock exposures containing fossils. Each exposure co...

The following diagram represents three rock exposures containing fossils. Each exposure contains a layer of volcanic ash (in red) that has been dated by the analysis of ²³⁸U/²⁰⁶Pb isotopes.

a) Place the fossils in the correct order according to their relative ages, from oldest to youngest.

b) Explain how you would estimate the potential age ranges of the C, G, and K fossils on the basis of the ages determined for the three volcanic ash layers.

(Question adapted from J. Dodick and N. Orion, “Measuring student understanding of geological time,” Science Education, 2003, vol. 87, pp. 708–31.)