The above map (here’s a link if your browser settings result in it not showing up) shows the relative location of some of the places discussed in the last several posts. The large “JAMESTOWN” lettering is a bit misleading, however, in that Jamestown Island was actually the blobby area which appears directly below #46. That might be clearer on the small map in this page. See also this “historic triangle” map.
Sunken Marsh Creek is located a short distance to the west from #31, along the south side of the James River as it moves in a northwesterly direction.
The map is from Charles E. Hatch, Jr., The First Seventeen Years: Virginia, 1607-1624 (Charlottesville: University Press of Virginia).
Another great resource is this interactive “Patterns of Settlement” map for the Jamestown area. Another tool is the Early Settlement up the Rappahannock page. Although not all the maps are oriented north and south, it shows the relative location of the Rappahannock as mentioned in the previous post in connection with the land grants of John Phips.