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Fragments of Pilgrimage - Seal (Barnes) Large Earthworks

  • 2 days ago
  • 8 min read
Seal Township Earthworks and Earthwork 'N' [Squier & Davis 1847, Plate XXIV, p. 162]
Seal Township Earthworks and Earthwork 'N' [Squier & Davis 1847, Plate XXIV, p. 162]
Home is the stable place to be transcended, goals the stable world to be attained, and camps are the rest stops for the journey from one world to the other.

Old Business


Aerials


I have obtained 7 frames on two reels from an aerial flight taken by the Agricultural Department, October 17, 1938. Four frames cover the possible locations of the Big Bottom site, one covers Piketon, one covers Earthwork N, and one covers Seal Works. I would like to thank Dirk at AAA Research in Washington, D.C. for his help in obtaining these images.


The Alembic

The 1938 aerial image shows a clearer and more complete view of the earthwork, plus two fragments which could be other earthworks, a possible mound, and an odd ellipse that could be historic. All of these anomalous features have been lost to a gravel pit.


The Alembic and other features [Fig. 1 Author]
The Alembic and other features [Fig. 1 Author]

Georeferencing 1938 imagery against current imagery is difficult because it is hard to find matching points. ODOT has imagery dating back to the 1950s that is already georeferenced. [ODOT 2026] These provide a better match. For this small region of interest, I was able to get a satisfactory match. I redid the circle and the walls. There are slight changes that are in the updated database. It is possible that the northern walls are not a mirror image of the southern walls, but because the southern part of the circle is smeared out, there is no way to tell. Burks used a 1934 aerial taken by Dache Reeves. [Reeves 1934] It is now possible to get an estimate of the width of the walls. I measured the NE and NW walls and the East and West circle walls separately. Both circle walls are wider due to smearing in the south. The NW wall is the sharpest, so I took 22.2 feet (6.77 m) as the approximate width of all the walls.


Outline of walls [Fig. 2 Author]
Outline of walls [Fig. 2 Author]
Updated outline and derived walls [Fig 3 Author]
Updated outline and derived walls [Fig 3 Author]

[QGIS Project]



Seal Township (Barnes) Earthworks


The earthwork consists of a large square connected to a large circle by a walled passageway. A creek divides the passageway, so the two large structures are on separate terraces. The square is what is called a 'standard Hopewell square'. The sides are divided into 8 sections, with 8 gateways and 4 gateway mounds in front of the middle gateways. These mounds do not contain bodies. One gateway has parallel walls of various lengths linking the structure to another, usually a circle.


William Romain, in Mysteries of the Hopewell, lists 7 square earthworks that have these features:


  • Liberty

  • Baum

  • Works East

  • Seip

  • Frankfort

  • Seal

  • Milford

[Romain 2000, p. 181]


I don't think this is anywhere near a complete list. Sometimes segments are fused or have different lengths, or mounds are moved or missing. Also, the two known Octagons can be considered a special case.


One interesting feature at Seal of both the circle and the square is that neither has an interior or exterior ditch. There are, however, three burrow pits around the walkway that could also serve as water features. The height of the walls is not given.


The Barnes house was built between 1803 and 1805 by Joseph Barnes, the co-inventor of the steamboat, originally from Virginia. The main part of the house is square with a pyramid roof and is across the road from the earthworks. The house is on a North-south axis like the earthwork square, and it is speculated that it was built with respect to the square, but the pyramid roof is said to be based on 'Masonic principles.' In 1847, Squier & Davis surveyed the earthworks, and in 1848, Abraham Lincoln stayed at the house, having read Ancient Monuments of the Mississippi Valley.  [Squier & Davis 1847] In 1900, the last passenger pigeon was shot near the house, and the wife of a Barnes descendant, Blanche Barnes, a taxidermist, stuffed the bird and displayed it in her house. The house currently stands in ruin. [Rice 2016]


Barnes House 2025 [Cahall 2025]
Barnes House 2025 [Cahall 2025]
Roof of the Barnes House [Cahall 2025]
Roof of the Barnes House [Cahall 2025]

What is the geometric relationship between the square and the circle? The circle can:


  • Inscribe the square: the square's side is equal to the diameter of the circle

  • Circumscribe the square: the square's diagonal is equal to the diameter of the circle

  • Have an equal circumference to the square's perimeter: 9/10 the square's diagonal is approximately equal to the diameter of the circle. Error %

  • Have an equal area: 4/5 the square's diagonal is approximately equal to the diameter of the circle. Error %


William Romain has proposed another relationship, that of a 30-60-90° triangle. He states that the square and triangle at Seal have this property. [Romain 2015, p.146] Looking at his sketch, there is something wrong. Using a triangle calculator, I put in his values:

Triangle using Romain's calculations. [Maple Tech 2026]
Triangle using Romain's calculations. [Maple Tech 2026]

Notice that this is not a 30-60-90° triangle. This triangle has a certain relationship between the sides:

Sides of a 30-60-90° triangle [Online Math Learning 2026]
Sides of a 30-60-90° triangle [Online Math Learning 2026]

Let us start with the square and redo the calculation. I don't know where Romain got his number for the sides, but I will use Thomas':


"The lengths of the sides of the square, as shown by the notes of the Bureau survey, are 854 feet east and west, and 852 north and south, being an average of 53 feet greater than Messrs. Squier and Davis’s measurements. The work is, however, very nearly an exact square."

[Thomas 1889, p. 15]


I'm using his exact numbers and not any average:

Diagonal of Seal Square using Thomas' measurements [Maple Tech 2026]
Diagonal of Seal Square using Thomas' measurements [Maple Tech 2026]

This diagonal is also the hypotenuse of the 30-60-90° triangle, so the short side is 1/2 of this. Here is the result:

Corrected triangle [Maple Tech 2026]
Corrected triangle [Maple Tech 2026]

Side b is our calculated value. The only diameter that we have at the moment is Squier & Davis' number of 1050. This differs from the calculated value by .5039%. Another possible relationship is equal perimeter and circumference, which differ by 3.321%.


Romain is correct in that this relationship exists at Seal, but his calculations in the book are incorrect.


Romain in Mysteries of the Hopewell states that the sides of the square fit inside the circle as an inscribed equilateral triangle. [Romain 2000, p. 50] The formula for this is: L = R \sqrt{3}. Where L is the side of the square, and R is the radius of the circle. I calculated this for a side length of 825 ft. and got a circle diameter of 909.38 ft. This differs from the Squier & Davis measure by 6.3%. Romain mentions a second method to construct what is called a vesica piscis [Wikipedia 2025], a lens shape created by two circles of the same radius. The long axis of the lens is the side of the square. Since the formula for the result is the same as that of the equilateral triangle, the error is the same. [Romain 2000, p. 52] 


To form a triangle, one needs three values out of the three possible sides and angles. Using whole numbers only, there are the equilateral triangle and the Pythagorean triples, such as the 3-4-5 right triangle. For two whole-number sides and a right angle, this forms a series in which the short side is x and the hypotenuse is nx. As n gets larger, the long side approaches the length of the hypotenuse. The builders of these geometric earthworks used these whole-number relationships to create these magic numbers, not whole numbers but embodied in their measurements.


The Walkway


"According to these authors the parallels running north to the circle are 100 feet apart and 475 feet long. According to the resurvey they are 68 feet apart, measuring to the middle line of each wall, and the average length 634 feet (the eastern 647, and western 621). The distance from the square to the break of the ravine is 427 feet for the eastern side, and 400 for the western, the width of the ravine 110 feet."


Again, Squier & Davis' measurements are quite different than Thomas. Thomas does not provide a drawing for this, and although the different wall lengths indicate that the walls angle west, he doesn't mention it. Squier & Davis have the circle directly north of the square; instead, the circle is also west of the square. Romain's measurement of the azimuth of the parallel walls as 348.5 degrees (N 11.5 degrees W bearing) is correct after matching the wall to the shadow of the wall in the 1938 aerial photograph. [Romain 2015, p.145]


The diameter of the Seal Circle


Errors in Squier & Davis' measurements were known from the 1880s. Unfortunately, at Seal, by the time Cyrus Thomas had James D. Middleton resurvey the earthwork, the circle was destroyed. However, in 2105, Jarod Burks found a small surviving arc of the circle using a 1938 aerial photograph.


Seal Barnes Earthworks on 1994 imagery [Burks 2011, p. 20, fig. 11]
Seal Barnes Earthworks on 1994 imagery [Burks 2011, p. 20, fig. 11]
Seal Barnes Earthworks on 1938 imagery [Burks 2011, p. 20, fig. 11]
Seal Barnes Earthworks on 1938 imagery [Burks 2011, p. 20, fig. 11]

To assemble the model, I first constructed the square and the gateway walls according to the Thomas measurements. Then I aligned the two according to the faint lines on the 1938 aerial. I created a circle using Squier & Davis' diameter of 1050'. I aligned the circle to the small visible arc. The parallel walls overlapped the circle by 2 feet on the west wall and 8 feet on the east. This suggests that the circle may be slightly smaller. Also, I didn't see how Middleton measured the distance of the walls; I always use center to center. Remember that the walls and the whole earthwork have an unknown thickness. It is extraordinary that the Scioto River had moved so much since 1938. The present-day river has cut into the embankment, so it might be possible to see where the circle was cut off. This would give two more points on the opposite side. I tried creating a circle from the small visible arc. I got a larger diameter circle, which I rejected. I used the Squier and Davis map to estimate the width of the gateways. The three central gateways were larger than the four corner gateways, but this could be an inaccurate map.

Seal Barnes Earthwork Final Map [Fig 4 Author]
Seal Barnes Earthwork Final Map [Fig 4 Author]

There are several 'situational' features to this earthwork:


  • There is no ditch, although several 'burrow pits' could be water features.

  • The square and the circle are on two different terraces.

  • The circle is not aligned with the square. The connecting parallel walls are at an angle, and where they enter the circle, they don't point to its center.

  • A stream breaks the parallel walls between the square and the circle. If there was some wooden or rope means of crossing, it has been lost to decay.


Table


Squier & Davis are unclear about where they made their measurements, so for the ones with extreme differences from Thomas, I separated the values.



  • QGIS Project

  • Seal Barnes Database


  • Software

  • 1938 Aerial

  • Georeferenced PDF of Map


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