Answer:
They can determine that a rock is 1.3 billion years old if 1/2 of the potassium has decayed.
Step-by-step explanation:
Geology refers to the solid, liquid, and gaseous matter that constitutes the solid Earth and the processes by which they change over time.
It includes the study of other terrestrial planets as well.
A geologist is a scientist who studies geology.
He studies rocks and the Earth sciences.
A geologist can determine that rock is 1.3 billion years old if 1/2 of the potassium has decayed.