TG: The word is spelled " SPALLS", not spauls. Spalls are as you described, piecies of flint that are knocked off a larger " Pre-form", or rock using a hammer stone, or hammer made of antler, or something other than a modern steel hammerhead. The stone or antler is just soft enough to allow a directed blow to break off a controlled size piece, with practice. If you try to use a steel hammerhead, you simply shatter the pre-form or rock in many directions.
I have a spalling hammer made of a piece of elk antler that a friend brought back to me from Colorado. It does take lots of practice to get a spall knocked off in a usuable size, But once you get a spall of the proper size, you can use smaller tools to shape it into whatever tool you are making.