Why does the vegetation change as you move inland across a belt of Sand dunes?

The answer is 1-plate movement along fault lines

Ibelieve it was because of the gas act in order to preserve fuel 

Evidence peice 1: millions of years ago existed the supercontinent pangea after millions of yearsnit broke into peices and formed smaller continents and islandsevidence peice 2: there is a massive fault line in san fransico and california that has the potential to cause massive earthquakes which supports the theory of fault linesevidence peice 3: mountains are said to be formed by earths tectonic plates crashing against each other for millions of years and eventually if forms a big point know as a mountain.evidence peice 4: the mariana trech is the deepest place (so far) discovered in the oceans of earth. it is so deep that you can literally see how earths plates are divided and or continents as well