We need the story or article
Answer:
age of rock is 2 million years
Explanation:

Where
is mass remaining
is original mass
n= t/t(1/2) , which is the ratio of time to half life
= 1000atoms
=250 atoms



t =t(1/2) *n
t(1/2) =1000000 years
t=1000000 *2
t=2,000,000 years
Hi the answer is cumulonimbus clouds. Hope this helps.