How to earths surface features indicate changes over time?

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

9. the history of life on earth is recorded in

What will happen if deforestation continue to destroy the green plant on the planet