They are indeed Earth Air, Fire and Water.
Everybody's take on tarot is different, but I view The Fool as holding the pure essence of each element (as they are yet, untapped).
The Fool himself is spirit in its purest form (as 'spirit' is usually what the Major Arcana represents), untainted by experience. Therefore The Fool is pure potential, if you think of it as the moment of conception, every possibility of what is conceived is there.
Hope that helps and enjoy your tarot journey.