Police say some of the damaged stones date to the 1880s and, because of the materials used, are irreplaceable.
The Journal Times reports 24 gravestones at Mound Cemetery were discovered damaged and pushed off their bases Monday.
The vandalism happened sometime between Friday and Monday. Police don't know who was responsible and if the vandalism was done by one person or a group.
Cemetery supervisor Steve Bedard is still assessing the damage. He says at least some of the stones can be put back together and brought upright.