Finding the Center of an 1875 Rock Mound

Kent McMillan · 2017-08-05T03:01:00Z

The other day someone - I can't recall who - was wondering how a surveyor determines the center of a rock mound of the sort similar to what was placed by Texas surveyors in, say, 1875 in Travis County, Texas to mark corners of land grants made by the State of Texas.Here is an example from this afternoon's work as the reconstruction of certain key elements of the complex patchwork quilt of land grants made by the Republic and State of Texas between 1839 and 1939 in the Hill Country near Austin continued.This rock mound was made on December 10, 1875 by Travis County Surveyor John E. Campbell to mark a corner of a certain 80 acre tract of land that one Frederick Kleineman had applied for as a homestead preemption grant under the terms of the law enacted in May of 1873 providing for grants to be made to actual bonafide settlers of vacant, unappropriated lands in the public domain.Mr. Campbell was the same surveyor who in 1879 made the rock mound that I posted photos of yesterday.I guess that in 1875, Mr. Campbell never suspected that a barbed wire fence would be built to enclose the adjacent tract or that a 6-inch dia. cedar corner post would end up approximately 9.0 ft. distant from where he made his mound. Otherwise, I'm sure he would have shifted his mound over a bit more than 3 varas in order to hit where the fence would be so that there would be no confusion. But he didn't and the mound has evidently survived in essentially perfect condition for 142 years.Here is a photo of the mound as I first saw it, an obvious rock mound hiding under a thick layer of cedar (Ashe juniper) duff. The first order of business was to use a whisk broom to clean off the duff and expose the size and pattern of the stones making up the mound.. The mound was 2.7 ft. in diameter both ways if one disregarded a couple of stones that had evidently slid from the mound into positions in which it was unlikely they were originally laid.By extremely advanced mathematics, I was able to compute that the center of the mound should be about 1.35 ft. from its edges. That point hit in a position around which the stones formed a radial pattern, so it was perfectly plausible as a candidate for the center of the mound.The metal detector indicated no ferrous survey marker was already in the mound designating its center, so I got the rock drill out and positioned the bit at the center of the mound that advanced mathematics had determined. Once the drill was fired up, I placed the bit in the position of the center and promply sank the bit about 18 inches into ground that is otherwise very rocky. I'd hit the hole of something at the center of the mound.Closer inspection revealed that my choice of the center coincided with where the remains of a very old and very rotten cedar stake that probably had originally been about 2 or 3 inches in dia. were. So, I pulled the rotten cedar stake and set my new rod and cap, REASONABLY CERTAIN that my designation of the center of the rock mound was within less than 0.10 ft. of corner as marked in 1875. And after returning a large upper stone to about the position in which I found it: The fence corner post was still about 9.0 ft. away.

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Strictly Surveying

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Kent McMillan

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Gene Kooper, post: 440650, member: 9850 wrote: Wow, I seem to have been promoted from Intellectual Vagrant to Geologist Dude.

Yes, vagrant In a Gene Lebowski kind of way.

Posted : August 8, 2017 8:28 pm

Kent McMillan

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Tom Adams, post: 440890, member: 7285 wrote: I am only making a small distinction about bearing trees being a natural monument. That is to say that I would hold a bearing tree as a "higher order of dignity" than an artificial accessory monument, as it can't be moved.

Sure, that's the obvious characteristic of natural monuments. That and the fact that they tend to be self-authenticating.

Posted : August 8, 2017 8:30 pm

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Finding the Center of an 1875 Rock Mound

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