Gravel will be our non-tradable in game token used for creating new pieces of land alongside $DIRT.
Players will obtain Gravel alongside $DIRT using the drill. They will need both tokens in order to form a piece of hexagonal land.
Gravel was created in order to prevent players from hoarding $DIRT in the ICO and creating land, expanding exponentially faster than the rest of the players slowly building up $DIRT from the drill and creating land through that way.
Gravel will have no real-world value and only has utility in creating land.