If stratum B lies above stratum A, B is the younger of the two. However determining the actual, or absolute, age of strata (for example, 3.5 million years old) is often difficult since the age of a fossil cannot be determined directly. The most useful tool in dating strata is radiometric dating of materials.

Is stratum D younger or older than Stratum C?

Formation D is youngest. Faulting is older than D, but younger than C. Figure 8.10. 8.2.

Is Basalt older than granite?

Basalt can form in a few days to months, whereas granite plutons can take millions of years to cool and harden. Basalt is more common in oceanic crust while granite is more common in continental crust.