Why can't scientists use carbon 14 to determine the age of an igneous rock?

Answer 1

The early Earth was molten and remained so for at least several hundred million years. The first rock solidified from melt roughly 4.25 billion years ago based on radioactive decay dating methods. Because only rock and certain mineral assemblages can be dated scientifically, the age of the Earth must be older than the oldest terrestrial rock of Earth origin. The oldest rocks that have arrived on Earth from asteroid or meteor impacts have been dated to the presumed age of the Earth, roughly 4.567 billion years.

Answer 2

Because they weren't there at the beginning. Because they don't know what the conditions were like, when earth began, they can only assume a certain unproven scenario, then calculate how long it would take to achieve the current scenario using only currently observed processes. Because natural processes may have varied in intensity, and because the starting model may not be correct, scientists can only guess how old the earth is.

Answer 3

Because rocks that were formed when the Earth's crust first cooled

have almost certainly been recycled by plate tectonics and erosion processes; the same problem applies to determining when living organisms first appeared, because the remains of these organisms have

probably been recycled as well.

Answer 4

Carbon-14 dating is used for carbonaceous dating, i.e. when plant material is associated with the sample. If the igneous rock sample does not have plant material on it, carbon-14 dating is useless.

Answer 5

Largely because igneous rock doesn't contain any carbon; any carbon would be vaporised in the heat of molten rock. Uranium is more commonly used to date igneous rocks.

Answer 6

You can, we did.