Carbon 14 is not normally used for dating lava flows. A different dating method such as Potassium 40 or Argon 40 dating is normally used for lava

What can carbon 14 dating be used on?

Carbon-14 dating is a way of determining the age of certain archeological artifacts of a biological origin up to about 50,000 years old. It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities.

How can you tell if a volcano is older or younger?

To get an age in years, we use radiometric dating of the rocks. Not every rock can be dated this way, but volcanic ash deposits are among those that can be dated. The position of the fossils above or below a dated ash layer allows us to work out their ages. The volcanic ash layer is dated as 507 million years old.