Civilization 4: Terrain

Base Terrain		Yield			Improvements Supported
	Grassland	2	0	0	Road, Railroad Farm (if irrigated) Cottage Workshop Watermill (if next to river)
	Plains	1	1	0	Road, Railroad Farm (if irrigated) Cottage Workshop Watermill (if next to river)
	Desert	0	0	0	Road, Railroad Watermill (if next to river)
	Tundra	1	0	0	Road, Railroad Farm (if next to river or lake) Cottage (if next to river or lake) Workshop (if next to river or lake) Watermill (if next to river)
	Ice	0	0	0	Road, Railroad Watermill (if next to river)
	Coast	1	0	2	-
	Ocean	1	0	1	-

Terrain Features		Yield			Health	Move	Defense	Improvements Supported
	Hills All Land	-1	+1			+1	+25%	Road, Railroad Mine Windmill Cottage (only on grassland)
	Forest Grassland, Plains, Tundra (Flat or Hills)		+1		+0.50	+1	+50%	Road, Railroad Lumber Mill All Other Improvements destroy Forest Negates river commerce bonus
	Jungle Grassland (Flat or Hills)	-1			-0.25	+1	+50%	Road, Railroad All Other Improvements destroy Jungle Negates river commerce bonus
	Floodplains Desert next to river (no Hills)	+3			-0.40			Road, Railroad Farm Cottage Workshop Watermill Building City Destroys Floodplains
	River all Land			+1				Flatlands Road, Railroad Farm (except on ice, desert) Cottage (except on ice, desert) Workshop (except on ice, desert) Watermill Source of fresh water
								Hills Road, Railroad Mine Windmill Cottage (only on grassland) Source of fresh water
	Oasis Desert	+3		+2		+1		Road, Railroad Source of fresh water Cannot build cities Cannot build improvements
	Fallout All	-3	-3	-3	-0.50	+1		Road, Railroad Cannot build improvements Can be scrubbed with worker
	Lake Water surrounded by land	+1						None Source of fresh water
	Mountains All except Coast, Ocean							Impassable Unusable
	Ice Ocean, Coast							Impassable except by submarines Unusable

Yield represtents the amount of Food, Hammers and Commerce the terrain  type gives when worked unimproved. For Terrain Features the number given is the bonus / malus to the normal value. Health indicates any Health bonus/malus the terrain gives to nearby cities. Move means the (extra) movement cost for this terrain, while defense is the extra defense. Please note that these bonusses stack. So a hills with a forest has +2 move and +75% defense. And while a Floodplains is given as +3 food, you will always see them as 3 / 0 / 1 because they are always next to a river.

The improvements listed are exhaustive. Improvements not listed can not be build. For the base terrain types, the resources listed are the ones that can be build without any terrain features. Special resources are not counted here. The specific improvement for a resource can always be built, no matter what the terrain type or terrain features.

The occurances for terrain features are what you normally see in the game. Using the world editor it is possible to make other arrangements, such as floodplains on top of grassland-hills. The bonusses  / malusses given in this table should still be correct, you should just add them for each terrain feature. You will never see such arrangements in normal games though.