This site near Wolf Rocks Road appears as a loose semicircular arrangement of stones about 500 feet across. The piles at the center of the arc are quite large.
Satellite imagery makes the ground look flat, and tree cover obscures details. Raw LIDAR data is available for this area. Here is a LIDAR scan of the site showing the contours of the ground with no z-axis exaggeration.
The mounds of rock in the arc are clearly visible. There are also some trails and old dirt roads at the northern edge of this area. There appears to be a large depression in the ground inside the arc.
Here is the view from the east.
Drawing a transect across the area from south to north gave this profile.
Clearly there is a steep slope to the south, then a deeper area and the slope of the hill to the north. It is not likely that a depression surrounded by rocks would have been used as a fort. The area inside the semicircle of rocks could have once been a gravel pit. Of course, there could have been another stony structure used as a fort, or suggesting a fort, which was mentioned in local land records.