From Populous Wiki
Totem Poles are magical devices which, when worshiped, trigger a effect. This effect will often grant the player access to previously unreachable parts of the world, or cause massive devastation to the Enemy. If you right-click on the Totem Pole, it will show you how many of your Followers are needed to worship that Totem Pole to begin. If you right-click on the pole again, you will see a red line next to the number of Followers and this indicates how long it will take.
Totem Poles differ from Stone Heads in that they cannot contain a discovery. If a discovery is assigned to a Totem Pole, it will be converted into a stone head.