Walsh's in Aghada Cork

Dating a grave marker

I have a grave marker with several relations on it and no dates can anyone put a date to it? Or know how I would go about finding a date The oldest marker in this cemetery is 1771 or the oldest identified marker? I dont know. Every other Walsh grave markers in the Aghada Old cemetery have dates
http://historicgraves.com/aghada-old/co-agdo-157/grave