This photo (lens cap for scale) shows a fairly smooth, flat surface consisting of tightly packed stones with desert varnish. A surface like this is called

The surface described in your question is known as a "desert pavement." Desert pavements are formed through a process of weathering and erosion, where smaller particles such as sand and silt are blown away by wind, leaving behind a layer of larger stones and pebbles. The desert varnish, which is a thin, shiny coating found on many rocks in arid environments, is formed by the accumulation of minerals, mainly iron and manganese oxides, which give the surface its characteristic dark appearance. This type of surface is commonly found in desert regions and plays a significant role in the landscape by protecting the underlying soil from erosion and helping to stabilize the environment.