watch the dvd Harry potter and the socceres stone. when you get to the main screen go to screen selctions click on the scene where harry is playing quiditch and watch for about one minute.when you watch this the person the person gaurding the goal posts when he gets knocked off of his broom he lands on sand but at the begning of the game and the end of the game you see that the entire field is made up of entirly grass.