Cti - brings up a good point. Have you done research on the property? looked at old land maps, insurance maps, etc from the 19th & 18th c and know if there was a house site or building,civil war camp, rev,1812 war, Indian wars, etc.. of some sort on the property. Are you finding any relics around this rock pile or near by it that would indicate something? are you seeing lot of broken pottery, glass, etc? If you walk 100 yards around this rock pile, are these rocks naturally occur in this area or were they brought in @ some point,etc etc. There is a-lot tooo it.. Best thing to do is hunt near the pile and see what artifacts are laying around and even digging test holes around the rock pile about 12-20 inches deep and see what you hit like broken glass,pottery,etc.. It could be many of things, i see these type of old rock piles a-lot some dating to the 18th c, some dating to the 1820s-1830s and lot of civil war rock piles of these sort that were used for riflepits, cellars, etc etc.. Do some research on the property and you may be in for a surprise.