Upland and lowland are conditional descriptions of a plain based on elevation above sea level. In studies of the ecology of freshwater rivers, habitats are classified as upland or lowland.
Cascadilla Creek, near Ithaca, New York, in the United States, an example of an upland river habitat
Amazon River near Manaus, Brazil, an example of a lowland river habitat
In geography, a plain, commonly known as flatland, is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands. Plains are one of the major landforms on earth, being present on all continents and covering more than one-third of the world's land area. Plains in many areas are important for agriculture. There are various types of plains and biomes on them.
The Kakanui Range dominates the eastern horizon of the Maniototo Plain of New Zealand
Montane plains as seen in Horton Plains in Sri Lanka.
A small, incised alluvial plain from Red Rock Canyon State Park (California).
A flood plain in the Isle of Wight.