In the earths mantle the convection currents pass through the mantle which then causes friction in the tectonic plates causing earthquakes,volcanoes or tsunamis
Depending on the period of time we are talking about, both things have been taking action. In the past, mostly the humans were adapting to the environment in order to survive, as they were still not powerful enough to start and shape up the environment as they wanted. This can easily be seen in the physical features of the people, like the mongoloids have developed fat bellow their eyes in order to protect them from the extreme cold, as well as reducing the sweat glands because they developed as a race in extremely cold environment.
In the more recent times, the humans have turned things around, and they are the ones that change the environment, not the other way around. Because the humans managed to reach a high level of technological advancements, they do not have evolutionary pressure to change, but they are the ones that make the environment adapt to them.
They use it to date rocks that are old and find the age. its not always accurate but close enough
