How can a volcano change or alter the surface of the earth?

Question

This is about volcanoes. and if you have any more info on them, please add them in too.

Answer 1

Now this is a subject with a lot of info available

http://geology.about.com/od/nutshells/a/...

http://volcano.und.edu/

http://www.geology.sdsu.edu/how_volcanoe...

http://volcanoes.usgs.gov/