Ashlar is prepared (or "dressed") stone work of any type of stone. Stone masonry utilizing dressed stones is known as ashlar masonry, whereas masonry using irregularly shaped stones is known as rubble masonry. Ashlar blocks are large rectangular cuboid blocks of masonry sculpted to have square edges and smooth faces. The blocks are generally about 35 centimeters in height. When shorter than 30 centimeters, they are usually called “small ashlar”.
Drawings by Frank Gaylard from: Fisher, Roger C. 1992. Visual Lexicon of the South African Dwelling. Cape Town: Unibook. p, 52-53.