Tools & materials:
Keyhole saw
Wood rasp
Wire brush
Dust mask
Acoustic ceiling tiles
Glue
Flock or sand
Paint
1. Glue several tiles together and let dry for an hour or two. I used three to give a cliff about 5cm high.
http://i.imgur.com/hkBc5.jpg 2. Use the wood rasp to shape the hill. This is extremely dusty work; wear a dust mask.
http://i.imgur.com/jcGRf.jpg 3. Use the wire brush to create strata. I made mine horizontal since the tile has somewhat of a grain to it. Perfectly flat strata are rare so some sort of dip or even folds would be more geologically realistic if you really want that level of detail. Keep in mind even steeply dipping strata can appear level if exposed from the right direction(cf. apparent dip). The layers will look more realistic if they are not all the same thickness. When you’re done, coat the strata in glue to strengthen them.
http://i.imgur.com/NY7Zk.jpg 4. Paint the cliff face black then drybrush with browns, greys or tans. You can add layers of geologic interest if you want, such as coal seams. The thin beds of alternating resistant (sand) and recessive (shale) layers give the look of a turbidite. I glued flock I made out of sawdust to the rest of the hill. If you’re making cliffs for North Africa, sand would work well here. Consider adding vines et cetera to the cliff face for Burma/Pacific terrain
http://i.imgur.com/A4QGz.jpg http://i.imgur.com/jtgTe.jpg