Blue Warrior said:
The name "Emerald Hill" does not imply the hill is made out of emeralds. It's called what it is most likely due to the fact that both acts have seven checkpoints in total, meaning you can potentially collect all seven chaos emeralds before completing the zone. One could also argue that the word is used as a color, not an object, in which case the name also makes sense.
Actually, I'm pretty sure it just means that it consists mostly of emerald colored grass. You'll notice that even though the cliffs you're hopping across are orange, the background is full of rolling green hills. In other words, its just fancier way to say "Green" Hill Zone.
I like to think that Emerald Hill and Green Hill are both the exact same place, and that because it was the place where Sonic first faced Dr. Robotnik has some kind of historical significance as well as some kind of connection to an emerald... but that kind of logic doesn't usually apply to the games.
Marble Garden Zone was named for the greenery with stone walls...
Mystic Cave Zone was so named because it was underground...
Sky Sanctuary Zone was so named because it takes place entirely in the sky...
Techno Hill Zone was named because of being a generic technological level...
More often than not, the name has no more significance than describing what the level looks like. As long as it serves that purpose, it doesn't matter what other relevance it may have to any kind of backstory or locations.
Same goes for Greenflower Zone. It's a generic grass level, and STjr never bothered trying to make sense of how it correlates to the "Greenflower City" in the cutscene because it doesn't really need to... Not that it wouldn't be amusing to try to make sense of it, as I get tons of enjoyment out of similarly useless elaborations of the other Sonic games, but it should not be something to worry about for the quality of the game.