Why are fossils in older rock layers less similar to present-day organisms than in younger layers?

What is earths lithospheric plates interact at

How does natural selection change thephenotypes within a population over time?

And give a detailed description! scientist observes the boundary between two tectonic plates for a decade and finds that no new volcanoes have formed over the course of her investigation. does this result support the theory of plate tectonics? why or why not?