How did aspects of Europe's geography (or geology) affect its history?
There are so many possible answers to this... I wonder if you might want to clarify a bit, to tell us if there's anything specific your class has talked about, etc. Keeping in mind that I don't really know what your class has talked about and what your teacher might expect you to know, here are some ways:
1. Assuming that you see England as part of Europe, its geology helped it become the home of the Industrial Revolution. Geology mattered because England was home to large deposits of coal. That coal provided England with lots of fuel that could be used to power machinery. By getting industrialized first, Britain was able to increase its power in the world.
2. Much of Europe, say from Poland over to France, doesn't have a lot of natural geographic barriers. This has mattered to European history because it made it easy for wars to be fought among the countries of that area. While Switzerland, for example, could be safe behind its mountains, Germany and France kept fighting each other and WWI and WWII were both fought largely in these large open areas of Europe.
3. The presence of the English Channel, making Britain into an island is important. This separation helped make Britain into a world power by protecting it from invasion. It also helped ensure that Germany could not invade Britain in WWII.
All of these are ways in which geology or geography has impacted Europe's history. There are more, of course, but these are a few.