Looking for a List of Less Common Topographical Terms

[NeonKnight]

to add to it, I will grab what you already have and add, with a short description:

Fen - A fen is a type of wetland fed by surface and/or groundwater
Bight - recess of a coast or bay
March - The border or boundary of a country or an area of land; a frontier. A tract of land bordering on two countries and claimed by both.
Dun - A type of small fort
Heath - heathland, low-growing woody vegetation, mostly consisting of heathers and related species
Moor - a type of wetland which is subject to frequent or continuous flood
Demense - In the feudal system, demesne (also spelled desmesne) was all the land, not necessarily all contiguous to the manor house, that was retained by a lord for his own use
Scree - an accumulation of weathered rock fragments at the foot of a cliff or hillside, often forming a sloping heap Also called talus.
Firth - A long, narrow inlet of the sea. Firths are usually the lower part of an estuary, but are sometimes fjords.

ALLUVIAL FAN - A broad, circular fan-shaped deposit of sediments found in deserts where erosional stream channels meet the valley floor and spread out, depositing the stream load.
ARROYO - A dry creek bed that fills with water after a heavy rain.
ATOLL - A circular coral reef that encloses a shallow lagoon.
CATARACT - A large waterfall.
CIRQUE - A bowl-shaped depression on a mountain that is carved out by an Alpine glacier.
KARST - A landscape composed of limestone features including sinkholes, caves, and underground streams.
LAHAR - A volcanic mudflow.
MORAINE - A ridge of unsorted and unconsolidated glacial deposits.
OXBOW LAKE - Crescent-shaped lakes, once part of a river meander, but now separated from the river and surrounded by land.