The meter-grid system, using spikes hammered into the quarry floor as grid nodes, is a common way to map paleontological and archaeological excavations. This method is invasive to the fossil-bearing horizon and can damage or even destroy buried specimens. This potential is greatest when the site is characterized by high bone concentrations, and/or specimen/matrix friability. A new portable mapping system based on a floating-grid was developed to circumvent these problems. This system also is well suited for excavations with uneven quarry floors. The floating-grid system extends over a quarry using retractable wires and mobile posts. It employs a mapping square that hangs from wires extended from a back wall or rebar posts.