An articulating composite surface covering mat and process of forming the mat are provided. The mat has multiple units having a regular, natural or irregular appearance, and each unit a flexible geogrid extending therethrough. Gaps are formed in the spacing between the units. A method of forming the mat includes forming the mat upside-down on a bottom surface of a bottom mold, locating a geogrid in a cavity defined between either or both of the bottom mold and a top mold, and placing the top mold over the bottom mold to form the mold assembly, sealingly engaging the transverse walls of the bottom mold and top mold where there is no geogrid, and adding the filler to the mold assembly.