added more terrain descriptions, based on Jetryl's originals

data/help.cfg

@@ -442,4 +442,25 @@ Most units have 50 to 60% defense in villages, whereas cavalry receive only 40%.
 <img>src=terrain/village-coast-tile.png align=left box=no</img> <img>src=terrain/village-tropical-tile.png align=middle box=no</img> <img>src=terrain/village-desert-tile.png align=right box=no</img>"
 [/topic]
 
+[topic]
+id=terrain_canyon
+title= _ "Canyon"
+text= "<img>src=images/terrain/canyon.png align=left box=no</img> 
+" + _ "A canyon is a gorge in the ground, leading to depths unknown. Canyons are noted for sheer walls which would take days to traverse. As far as gameplay is concerned, only units capable of flying over canyons can cross this terrain."
+[/topic]
+
+[topic]
+id=terrain_lava
+title= _ "Lava"
+text= "<img>src=images/terrain/lava.png align=left box=no</img> 
+" + _ "The dangers inherent in trying to walk on lava are fairly obvious. This terrain can only be crossed by those units capable of flying a considerable distance above it."
+[/topic]
+
+[topic]
+id=terrain_ford
+title= _ "River Ford"
+text= "<img>src=images/terrain/ford.png align=left box=no</img> 
+" + _ "When a river happens to be extremely shallow, passing over it is a trivial matter for land based units. Moreover, any creature best adapted to swimming has full mobility even at such places in the river. As far as gameplay is concerned, a river ford is treated as either grassland or shallow water, choosing whichever one offers the best defensive and movement bonuses for the unit on it."
+[/topic]
+
 [/help]

data/terrain.cfg

@@ -468,7 +468,7 @@ unit_height_adjust=-4
 
 [terrain]
 symbol_image=lava
-id=ford
+id=lava
 name= _ "Lava"
 char=l
 aliasof=X