Flat formation (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">flat formation</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for mesa that I've seen before include "Isolated flat-topped hill" , "Flat tableland with steep sides" , "In the US south-west, a steep-sided flat-topped hill" , "Flat-topped mountain" , "Flat hill" .)
(Other definitions for plateau that I've seen before include "Quiet time" , "Levelling off" , "High plain" , "Reach a level" , "Elevated flat land" .)