@SallyStrange oooh thank you. That's a really good summary for someone like me with no real prior geology knowledge.
One additional question though, Jamaica - as far as I'm aware has mountains but also only has fine sand beaches - is this the exception to the elevation rule ?
Although I'm not sure if Jamaica became an island through land erosion/sea encroachment of a larger land mass or if it sprouted out of the sea due to volcanic activity .. ?