If you look at it from google earth and use the tilt feature, you can get a better idea of the topography, by looking at the shadows. The interior lines are actually big hills, pitched to each side. There are large tire tracks all over the place, and there are three big culverts on both the north and south sides of the retained areas, leading to the larger inner area. The inner area also has a large mound near the center with something in the center. No equipment shown in the pics. Not sure why those two parcels are so oddly shaped, since most other parcel shapes are nothing like it. You can see that the surrounding property was planted pines, so was likely owned by St Joe at one point in time.