What term describes the flat areas of upland found in various landscapes?

The term that describes the flat areas of upland found in various landscapes is "mesas." Mesas are characterized by their elevated, flat-topped landforms that rise sharply from the surrounding terrain. They often have steep sides and can be found in arid and semi-arid regions. Mesas are typically created through the processes of erosion and weathering, which remove the softer materials around them, leaving the harder, more resistant rock on top.

In contrast, valleys refer to low areas between hills or mountains, and deltas are landforms created at river mouths where sediment is deposited. Plateaus also involve elevated flat areas but are generally larger and can have varying elevations across their expanse. While both plateaus and mesas can be flat-topped, mesas are specifically distinguished by their smaller size and more pronounced edges, thus highlighting the defining characteristics of these landforms.