There are only seven base terrains: Plains, Forest, Mountain, Desert, Ice, Water, and Volcano. These terrains are exclusive. Each square on Earth may have only one.
Each square on Earth may have one of each type of special terrain, in addition to the base terrain which underlies them. Most base terrains have limitations on which base terrains they can exist on. Once a special terrain is placed, it "locks" the base terrain into remaining one of the base terrains appropriate to the special terrains, though the base terrain can change within these limits.
Once Era Centrum begins, this limitation no longer exists. If a square is changed by a jistory power into a new base terrain, any special terrains that cannot exist in the that base terrain are simply destroyed. See the special notes below.
In the table, the base terrains are encoded as follows: P=Plains, F=Forest, M=Mountain, D=Desert, I=Ice, L=Land (any non-water), C=Coast (land adjacent to water), W=Water. No special terrains can exist in a volcano square, even those that say "any".
|Bad Juju||half-cost for negative powers||L+|
|Blessed Land||counteracts negative powers||L+|
|Caves of Fear||worship Fear and Dark or 25% chance religious turmoil||L|
|Chaotic Terrain||base terrain changes randomly||any|
|Chasm||exists on edge of square, impassable||any|
|Crop Circles||mana to Art if no city||P|
|Dead Zone||0 pop||L+|
|Death Trees||kills excess population||F|
|Defensible Location||+3 defense||L+|
|Doldrums||impassable to sea-faring||W|
|Fertile Land||+2 pop||L|
|Fountain of Youth||no death||L|
|Game Animals||+2 pop||L|
|Game Birds||+2 pop||L|
|Glacial Ice Pack||spreads||I*|
|Great Erg||impassable to non-desert||D|
|High Winds||no aerial bonuses||L|
|Hot Spot||starts volcanoes||any|
|Hurricane Zone||starts hurricanes||W2|
|Impenetrable Forest||impassable to non-sylvan||F|
|Impenetrable Mountains||impassable to non-aerial||M|
|Mineral Resource||+3 wealth||L+|
|Mirage||as Paradise until city, then as Dead Zone||any*1|
|Mithril Deposit||+10 wealth, +1 mil||M|
|Mountain of the Gods||double mana from worship||M|
|Natural Crossroads||+5 wealth||L|
|Paradise||+5 pop, +5 wealth, immune to negative powers||any*1|
|Plague Zone||hidden; starts a plague when entered, one time only||L|
|River||+1 wealth, +1 pop||L|
|Rough Tides||impassable to amphibious||C|
|Stable Ground||no earthquakes or volcanoes; cancels Unstable Ground||any|
|Stonehenge||worship Light or religious turmoil||L|
|Storm Front||starts cyclones||P|
|Stormy Seas||25% loss when crossed with sea-faring||W|
|Superior Metals||+1 mil||L+|
|Temple of the Sky||extra mana||L|
|Unstable Ground||starts earthquakes; cancels Stable Ground||any|
|Void Gate||+10 wealth, demon cults||L+|
|Well of Magic||+7 wealth to magic cultures||L+|
|Writings of the Gods||teaches knowledge, one time only||L+|
Though they exist in Heaven, the following things provide mana just like terrains: the Sun, Moons, Constellations, and Demesnes.
Though not terrain in the usual sense, certain living creatures can be created during Era Aleph which provide mana just like terrains. However, instead of existing in one spot they move around the map with various effects (usually attacking local populations). The five types of mobile "terrain" are: Dangerous Beasts, Dangerous Birds, Monsters, Sea Monsters, and Pestilence Rats.
Finally, mortal cultures can build cities and great cities. These function just like a special terrain which can exist in any square, as long as the population can live there.