Evidence provided by conjoined bone and lithic fragments from Old World sites such as Gombe Point, Meer II. Terra Amata, and Hortus shows that disturbance during burial, or following deposition, may affect archaeological assemblages to a much larger extent than previously imagined. The existence of an apparently undisturbed matrix, or of a finely stratified sequence, is not enough to rule out vertical displacement of artifacts and, in the case of multilevel sites, mixture of assemblages. As a result, many inferences based on fine stratigraphic controls may be open to question. Conjoined pieces can be used to test the presence and extent of stratigraphic disturbances that have not left clear, macroscopic traces in archaeological sediments and which have, therefore, few chances of being recognized.