​MESA (Span. mesa, from Lat. mensa, a table), in physical geography, a high table-land capped with hard rock, being the remnant of a former plateau. This type is general where strata are horizontal. In the process of denudation the hard rock acts as a flat protective cap preserving the regions between stream valleys or other places where denudation is especially active, in the form of “ table-mountains ” or “ fortress-hills.” Many examples are found in Spain, North and South Africa, the Bad Lands and Colorado regions of North America, in Arabia, India and Australia.