<span>Scientists choose where are units of time began and ended based on major changes in life forms at certain times</span>
Devils tower this was the first national monument in wyoming.
Answer:
we need tropical rain forests because they produce oxygen and clean the atmosphere to help us breathe. They also provide us with medicinal plants and may be the source to cure deadly diseases.
It has gone through four half-lives of carbon-14 (5730 years<span> x 4 = </span>22920 years<span>)
It is 22920 years old.
Hope this helps!</span>
Temperate forest is the ecosystem which usually supports thick forests of deciduous trees.
