Terrain

Beach
Beaches can only be found around lakes. They're the only source of sand.

Cave
Caves can be found randomly throughout the world on south and east facing cliffs on all terrain except mountain. Caves contain stalactites, which function similarly to boulders (can be converted to runestones or used as a limited source of stone), and cavebulbs. Cavebulbs can be cooked into one of the few foods in game to generate PSY FEP, and as such can be quite valuable. Caves can also contain minerals if prospected.

Properties

 * Caves never have a minimap and as such are impossible to map using cartography, making them difficult to explore. Using the large amount of stalactites to make signs out of runestones can prove helpful.
 * Caves are dark if you're not using nightvision with Pacho's client. Torches can help out immensely in that case. Cavebulbs also will cause you to glow for a while if eaten (but you shouldn't waste them for that), as well as a certain ancestor worship prayer.
 * Caves may have multiple entrances, and can be QUITE large or quite small.
 * Cave walls themselves cannot be mined, but caves may contain mine entrances.
 * Items placed inside caves do not decay, making them great for storage, if necessary.
 * Caves can be used to age cheeses.
 * Shallow water in cave may contain cave clay, an ingredient of bone clay, used with feldspar to make porcelain.

Forest
Forests include the subtypes conifer and broadleaf. The only difference between the being that they spawn different trees. The trees of one type grow more slowly in the other type.

Broadleaf trees

 * Apple
 * Birch
 * Hazelnut
 * Maple
 * Oak
 * Mulberry

Conifer trees

 * Fir
 * Pine

Objects which spawn in both
Foraging required:
 * Anthill
 * Bear
 * Boar
 * Deer
 * Fox
 * Rabbit
 * Earthworm (found by digging)
 * Silkmoth
 * Blood Stern
 * Blueberries
 * Chantrelles
 * Rustroot
 * Spindly Taproot
 * Stinging Nettle
 * Wild Windsown Weed

Natural flow of terraforming
Most terrain in the game is set to remain as the type it is naturally. A natural grassland, for instance, will not succumb to trees, but hearthling intervention can cause the natural lay of the land change in the following ways: As of right now, only fir trees have reproduction enabled while the devs work out balancing the terraforming system.
 * Planted trees will cause the land surrounding them to randomly over time convert to the tree's native terrain. Fir trees spawn conifer forest and oaks spawn broadleaf forest, for instance.
 * When trees are removed, forests will develop into a grassland.
 * Grassland can develop into a moor. Letting grassland recover naturally from being plowed gives a small likelihood of this happening.
 * Moor can develop into a heath by the same method as grassland to moor.
 * Overplowing any ground can cause the ground to become mudlfat. Animals grazing on grassland also causes this.