Military Fox Hole
- Thread starter bobpbx
- Start date
It definitely has a slope, and is about 30' to 40' in diameter. But seems to be only 2(?) feet deep.
I’ve been playing with the 3-D LiDAR too. I’ve seen a few spots where the top of small hills were dug out. I’ve been thinking they were digging out pebbles to possibly make concrete. That one seems a bit remote but maybe it was for nearby cranberry bogs. Slightly east of that spot there’s a few smaller ones also on an elevated hill.
Somebody told me about the sand mines....they would scoop out an area about 40' long and eventually 6' deep to see if the sand was worth mining. I saw a lot of that in Lacey township.
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Bob, I had wondered about this before, and my thought is that it is a borrow pit for a causeway on this old road: https://boydsmaps.com/#16.00/39.689518/-74.715691/historic62k/0.00/0.00
Using the lidar elevation tool, I'm seeing a depth of 4 ft. @Boyd, can you speak to the accuracy of the lidar elevation?
Keep in mind that they essentially truncated a small hill; the original elevation at the crest was higher than the present day edge of the pit.
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I don't know what the "lidar elevation tool" is. Do you mean the elevation readout on the map?
That is the same data used to create the surface on the 3d maps. In the pines, it has a theoretical horizontal accuracy of +/- 1.2 meters. Vertical accuracy is another matter that could be more complex. If you look at the mapinfo there are metadata links that might give some guidance. The "official" answer is that I make absolutely no representations as to the accuracy of elevation readings.
My sense is that they are pretty good though, you can compare the readout to benchmarks on the 24k topo maps and they are quite accurate up in the mountains, where a benchmark might be only off by a few feet at an elevation of 3000 feet. But, of course, in a really flat place like the pines, an error of a few feet is a much more substantial percentage.
Here's a benchmark at the intersection of two roads near that pit. The topo says 38 feet, my readout says 36.75 which strikes me as pretty good.
But keep in mind, the georeferencing of those 24k topo maps is not very precise. In creating my elevation dataset, there are multiple steps where the source data was re-sampled and that could result in some errors too.
IMO, the elevation readings are pretty accurate - but that's just an opinion.
For example, Garmin's 24k topo maps have DEM with a resolution of only +/- 30 meters, which is really crude. That is also the same resolution you will get from the USGS EPQS (Elevation Point Query Service).
I should mention, there's a bug where the elevation reading will be wrong when you first open a link - it is showing as 385 feet in this case. But if you move the map just a bit, it will show the correct reading. That's a tricky bug that I spent awhile on and couldn't figure out. Need to revisit that one day....
That is an interesting supposition Watson. I'm going to field test it. Thing is, I only see two very narrow trails up to the spot. That may be motorcyclists going up to see what it is (time and time again, maybe?).
You are thinking of aggregate John. I don't like that idea, that small a hole way the hell out there (as Fred Brown would say it) is not commercially feasible, and in this case, they didn't get much. I'd say aggregate is readily available at any of the sand mines as a by product of digging for the sand grains. I do recall that the pinelands are a reverse landform. The harder sandstone resisted weathering, so that sedimentary rock form is usually at the higher elevations. But that's not aggregate.
This topo says the same. I think, really, that the upland here is only 10 feet higher in elevation than the stream.I don't know what the "lidar elevation tool" is. Do you mean the elevation readout on the map?
View attachment 19085
That is the same data used to create the surface on the 3d maps. In the pines, it has a theoretical horizontal accuracy of +/- 1.2 meters. Vertical accuracy is another matter that could be more complex. If you look at the mapinfo there are metadata links that might give some guidance. The "official" answer is that I make absolutely no representations as to the accuracy of elevation readings.
My sense is that they are pretty good though, you can compare the readout to benchmarks on the 24k topo maps and they are quite accurate up in the mountains, where a benchmark might be only off by a few feet at an elevation of 3000 feet. But, of course, in a really flat place like the pines, an error of a few feet is a much more substantial percentage.
Here's a benchmark at the intersection of two roads near that pit. The topo says 38 feet, my readout says 36.75 which strikes me as pretty good.
View attachment 19086
But keep in mind, the georeferencing of those 24k topo maps is not very precise. In creating my elevation dataset, there are multiple steps where the source data was re-sampled and that could result in some errors too.
IMO, the elevation readings are pretty accurate - but that's just an opinion.
And this is a dune.
Sorry, not following you here. What topo and what does it "say"? Are you just talking about the elevation contours? If you are talking about the elevation readings in my app, they always come from the same database, regardless of which map you are viewing.
Yes, aggregate is the word I was looking for but escaped me. Sand and gravel are the only things I can think of someone looking for in a paleo dune. Whether to use nearby or possibly prospecting , that would explain the small test holes to the east too. The funny part is I’d bet that location was more accessible 100 years ago then it is today. Though I have heard stories of pirates coming inland and burying treasure in the pines and people looking for it. You could be on to something
Gabe is spot on with the borrow pit theory for gathering material to construct a stream crossing. That road shows up in the 1870 Vermeule maps as well.
There are several of these pits in my neck of the woods, all dug in closely adjoining uplands to build stream crossings and dikes along the Albertson.
There are several of these pits in my neck of the woods, all dug in closely adjoining uplands to build stream crossings and dikes along the Albertson.
I was going by the topo lines, or abscense of them. They are 10 feet, and there is only a 30 and a 40 in the neighborhood. 1953 Atsion Quad.
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Gabe, this 2020 aerial gives credence to your theory. A straight line blockage at the crossing. Odd that an elevation change is not shown on any of the lidars.
Interesting to look at the topos through the years. The landcover on the Cook map is significant, it shows a pine forest adjacent to the road with a narrow band of wetlands along the stream then a larger wooded wetlands to the North along the Meschetac...(whatever) Branch.
https://boydsmaps.com/#15.00/39.689518/-74.715691/cook/0.00/0.00
Then the 1949 topo shows a huge swamp across that whole area, with no road and no stream. Is this just poor cartography, or was that whole area actually flooded? The earlier maps all showed those features, so it's not like they didn't know there was a road.
https://boydsmaps.com/#15.00/39.689518/-74.715691/pines1949/0.00/0.00
Cool, I see. Of course, elevation contours are just a low-resolution generalization of real terrain, which is much more complex. I used the older 3-meter LIDAR to generate 2-foot contour lines on my 2017 topo but wasn't very happy with that in the end. However, it shows your "foxhole" very clearly.
https://boydsmaps.com/#17.00/39.690055/-74.716839/pinesHD/0.00/0.00