Ancient fossils can be bones, imprints, shells and other things. They each tell us something different, but how did scientists create Earth's history over billions of years? The plant imprints in rocks helped them immensely. These imprints helped showed how Earth grew. These imprints showed what environment the Earth had millions of years ago.
The Grand Canyon's walls have millions of years of geological history in them. The "stripes" are actually rock layers that happen over time, stacking on top of each other, younger over older. For example, if you take a picture a day and just lay it down and slowly stack it up, the older ones will be toward the bottom of the stack, not toward the top. This is called superposition.
The Grand Canyon also has places in the walls where layers of rock seemed to have grown upward instead of to the side. This shows a cross-cutting relationship. The rock cutting through the other layers has to be younger than the other layers because you can't cut something that's not there. It's like trying to cut a pizza that's not there, although some people could argue that imagination is key.
The idea of evolution presents that all species evolved and adapted to their environments over time. Charles Darwin is the person who created this thought in the first place. Overpopulation and limited resources presents the idea that species evolved themselves to be able to mate successfully and gather food successfully.
This can lead to evolution by getting certain traits that help the species survive, such as the cheetah's "Cleopatra eyeliner". The "eyeliner" is actually a fur pattern that helps keep the sun out of their eyes. Bears go into hibernation so that they can sleep throughout winter and still be alive.