types:
grot,
spelonk
a geological formation consisting of an underground enclosure with access from the surface of the ground or from the sea
bergmassief,
massief
a block of the earth's crust bounded by faults and shifted to form peaks of a mountain range
inham
the point where a stream issues into a larger body of water
bekken
a natural depression in the surface of the land often with a lake at the bottom of it
bed
a depression forming the ground under a body of water
grot
a small cave (usually with attractive features)
hoogland
elevated (e.g., mountainous) land
duinpan,
pan
a depression hollowed out of solid matter
geiser
a natural spring of water at a temperature of 70 F or above
ijskap,
landijs,
poolkap
a mass of ice and snow that permanently covers a large area of land (e.g., the polar regions or a mountain peak)
berg
a land mass that projects well above its surroundings; higher than a hill
richel
a long narrow natural elevation or striation
vallei
a long depression in the surface of the land that usually contains a river