The opening descriptions of the forest suggest that what Tom will find there will be ?

One day when Tom had ventured to a far part of his neighborhood, he decides to take a shortcut back through a nearby swamp. It was a dark and gloomy route, somewhat treacherous, and the swamp only had one piece of firm land. This piece of land was once a stronghold for Indians during their war with the local colonists, but nothing remains of their former fort except a few embankments. Tom stops at the old fort site to rest for a while, and while leisurely turning up some soil, digs up a cloven skull with an Indian tomahawk buried in it. I expected he would see a ghost spirit of an Indian.