The Ekonk Hill Petroglyph Site, An Archaeogeodesy Perspective

1998 by James Q. Jacobs

In Nov. of 1995, the Arizona Republic reported on a Boston Globe article about a set of carved rocks found in rural New England. Several other papers carried the same reports. I summarize the 1995 reports as follows:
A recent discovery in Sterling, Conn., an arrangement of petroglyphed boulders, may add to our understanding of the prehistoric peoples who lived in the area.

Some Native Americans have said the site could be 10,000 or more years old. Alignments at the site indicate a possible association with agricultural cycles. The earliest evidence of corn planting in the area dates to 1,300 years ago. John Brown, tribal-history preservation officer for the Narragansett, thinks the rocks indicate celestial knowledge. ''There is direct concern about the safety of these rocks,'' Brown said in the Boston Globe article. ''The destruction of such a thing would be a terrible loss.'' Representatives of the Narragansett and Mohegan tribes are concerned that publicity about the site could lead to damage.

State archaeologist, Nick Bellantoni, affiliated with the University of Connecticut, was quoted in the Boston Globe as follows, ''I'm rather confident that they are probably Native American in origin, but I have nothing to compare it to. I think it is very much worth investigating. We just want to make sure that people respect the site.'' Bellantoni wants to further investigate the site.

Residents of the neighborhood knew about the petroglyphs on the largest of the three granite rocks. These include animal heads, including a possible a mountain lion with a quartz outcropping for teeth. The boulders, weighing several tons each, are carved with several oval and circular shapes. George Molodich, a dairy farmer nearby, exploring near the carved rock and found a second with petroglyphs, and a third rock with both petroglyphs and iron-oxide paint. Molodich, has since found another 26 boulders describing a near circular form. Many also have markings.

David R. Wagner, an instructor at Quinebague Community College, has made several sunrise trips to the location. Wagner concluded that the three rocks might represent a corn planting calendar. Wagner has published a report with maps.

During 1996, I communicated with Professor David Wagner, who provided his articles (The Ekonk Hill Petroglyphs, Aug. 1995, and The Ekonk Hill Petroglyphs Update, Jan. 1996), a location map, and a map of the triangle of three large boulders. According to Mr. Wagner the three boulders form a triangle with sides measuring 190, 182 and 79 feet.

I calculated that the acute angle of the triangle equals 24.40 degrees.

From a USGS topographic map I determined the site's coordinates to be 71.8631° W. longitude at 48.3472° colatitude. Given the following:

  • latitude equals 41.6528° at the site,
  • obliquity of the ecliptic equals 23.439291111°, and
  • inclination of the lunar orbit equals 5.1453964°,
level horizon lunar minor bearing (w/o refraction, etc.) [(23.43929 - 5.1454)° / (41.6528° cos)] = 24.484°.

I therefrom conclude that the Ekonk Hill is a site worthy of further study, especially so because the site combines rock art with possible place marks in the form of arranged boulders. At Ekonk Hill's latitude, the angle 24.484° insinuates lunar minor. To accurately assess this correspondence of 24.4° angles, an exactive survey measuring both boulder to boulder and petroglyph to petroglyph distances in three dimensional space is needed. Only the most precise possible measurements will allow equating the angle with epoch.

If the Ekonk boulders record the level horizon lunar minor angle, the angle might indicate the approximate date the boulders were placed and, possibly, changes in angle during an epoch of site use and inscription. One thousand years ago the lunar minor angle  (w/o refraction, etc.) was 24.658°. Given a 190 feet hypotenuse the short triangle side changes only about six inches per 1000 years, if aligned to lunar position. Given the size of the boulders, only petroglyph to petroglyph measurements can provide such accuracy. At best a rough age estimate will be possible. This should illustrate the need for exact measure.

The three boulder configuration is either coincidence or the petroglyph field demonstrates evidence of knowledge of the local latitude's lunar rise-set geometry. If the petroglyphs producing the lunar minor angle are an intentional arrangement, then their iconography may be related to lunar minor. Their context may be relevant to their meaning.

Another discovery of relevance may be the latitude to longitude proportions at Ekonk Hill. Using the IAU accepted standard for the figure of the meridional ellipse (see Astronomy Formulas Page), I calculated the proportion of one degree latitude to one degree longitude for the Ekonk Hill latitude. The result is 69.0214 miles : 51.7602 miles (1.3333363 : 1 or 4.0000 : 3). This is a latitude specific property and both the proportions and numerics (of a 3 : 4 : 5 triangle) should be included in any considerations of the site and the petroglyphs. I consider this site feature to be significant. It might demonstrate an exactive knowledge of latitude and the correspondent spatial and mathematical properties of place. Perhaps this is the reason why the monument was placed at the latitude where it is. The latitude where the proportion is exactly 4 : 3 is 41.65263°, an almost nil margin of error.

The largest earthwork in North America, Monks Mound at Cahokia, is located at the latitude where tangent equals 0.80 with equal precision. In fact, if secular polar motion is used to date Monks Mound the results concur with radiocarbon measurements.

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Background is McKee Man, McKee Spring, Utah