Ancient Astronomy in Portuguese 'Mesopotamia', a summary in English Portugal

Submitted by Magalhaes on Wednesday, 19 April 2006 Page Views: 6249

Country: Portugal In 2001 we bought a small house in Santiago do Escoural, in Central Alentejo, Portugal. I had a passing interest in "funny stones", but nothing to be afraid of. A lunch acquaintance who is a potter, gave me, Zeus knows why, an old photocopy about the restoration of some menhir - the Tojal menhir - including a military map copy with half a dozen "antas" and menhirs marked on it. And so my interest took hold.

By then I had, of course, already visited the tourist attractions - The Almendres stones, the Anta Grande do Zambujeiro, the Escoural cave, the dolmen-chapel of N. S. do Livramento at S. Brissos, and couldn't possibly miss the Anta do Pinheiro, on the roadside.

Before I proceed, I must say that I will use the word "anta" for the local form of dolmen because it is primitive, more primitive than a regular passage burial chamber. They have a polygonal chamber with a wide opening, 5 to 7 upright stones.

So, the stuff is possibly quite old, older than the usual. There are instances in which archaeologists will assure you that the burial artifacts, and sometimes the added stones that made the transformation into a burial site, are definitively later than the initial stones. I would quote Bob Holdam: "One obstacle to understanding the purpose of the antas is a lack of clearness about their actual age. Artifact associations have dated them to about 3000BC, but it is not known whether the artifacts were contemporary with construction or were placed long after the antas were built."

Anyway...

In 2002, I visited these monuments, GPS in hand. If many were in a decent, at least recognizable state, most were in the "So, where is it?" state: a few scattered stones, suggesting really nothing.

Even later I fell upon a Montemor-O-Novo tourism brochure with 14 megaliths. Now, something is going on here, or else it's just another of those inflated informations. So I started visiting them and, to my surprise, they were magnificent -- at least to a beginner.

Last year I fell upon some loose information: that a few years ago someone had solved a few equations and found out that there are only two latitudes in the world in which, in some nights, you can have the (full?) moon on the zenith, and that these were the latitudes at which Stonehenge and Almendres are.

This year I found the site where the local arqueologists and historians are publishing their material, here. It's about that material that I write here, as most of the web site is in Portuguese. In summarizing it I hope not to murder the meaning of the original too much. Do look up the site for images, maps, coordinates, graphics, etc.

The Almendres cromlech, which is elliptic roughly in the East-West direction, was discovered in 1964 -- at least by an archaeologist; although the megalithic sites in the area of Central Alentejo have been researched since the 19th century. By the 1960s, Thom's, Hawkins' and Hoyle's work on Stonehenge were either known or in the process of being published. Hence several similar studies were done over the world, and why not Almendres? It was admitted that, given that it had some 93 stones, you just had to chose a direction and then find the suitable pair of stones lined up with it.

In 1974 an archaeologist just made the simplest experiment possible: he scratched his head at Almendres at set himself forth in the direction of sunrise, until he bumped on a fallen menhir near the Monte (rural house) dos Almendres. [Most likely the one now known as Menhir dos Almendres, but I'm not sure yet.] In 1980 it was found that, when viewed from the cromlech, that menhir points to the sunrise in winter solstice, and vice-versa regarding the sunset.

A stone that called for some attention was one cut at the top, with dimples on it (number 8). It was at a suitable position within the ellipse; but the other pair, a big one on the other focus (number 39), was fallen. After it was put back into its socket, and some trees were cleaned up, it was possible to observe that the sunrise and sunset, at (megalithic?) spring equinox, occur along the line joining the two stones. The dimples on Number 8 might serve as places to put suitable references to guide the eye, accompanying the sun's movement, even in different years (apparently with a period of 33 years).

The cromlech has 93 stones, which makes the minimum to count a quarter of the year, providing for variations. There was no hint of a "megalithic yard".

A leap of ideas then occured. Actually it was thought that the hill of Évora would have provided the reference for the sunrise, but there was no further reference to it. Instead, the experiment was made with the close vicinity of the menhir of Perdigões and the Monsaraz hill, a long baseline, and yes, it was so (and, of course, vice-versa for the sunset).

Then, it was found that, at winter solstice, when viewing the sunset from the rather destroyed "antas" on the roadside near Valeira, the sun would set over the Portela de Mogos cromlech. I must say, though, that the local notion of stone ring looks more like an horseshoe widely open to the East, not always, but many times.

At that point it seemed that there was not only an astronomical relationship within the megaliths, but also between megaliths, and between megaliths and references in the horizon, "landscape references".

It was also noted, although not much can be done with it, that many local megaliths concentrate, or line up, along ridges that split three hydrographic basins: those of the Tejo, Sado and Guadiana rivers. The Almendres cromlech is very near the junction point for these three basins. This region is half-jokingly but descriptively known as "the Iberian Mesopotamia", if I'm not too wrong, since Roman times.

From Almendres and roughly to the East you can see the tops of the Evoramonte, Caramelo and S. Gens-Castelo hills, on the Ossa hills (and on the Tejo-Guadiana basins separation.) These happen to coincide with: (1) moonrise at lesser standstill, northernmost extreme, for Evoramonte, (2) sunrise at summer solstice, for Caramelo and (3) moonrise at lesser standstill, northernmost extreme, for S. Gens-Castelo. To the West, (4) the zero degree line goes through the top of the Conde Hills, and (5) during the lesser pause the moon sets, at the northernmost extreme, over S. Sebastião, where there are two menhirs.

But there's more, of course. Now, the other six enclosures are in three pairs, with each element distant by 1-2 km. Of these pairs, at least one is on the ridge that divides the waters among rivers. The elements in each pair can be seen from each other, but not the pairs. There are two pairs for the Tejo basin (with difficulty - let's call it pair A), two for the Sado basin (definitely, and let's call it pair B) and two on the Valverde creek basin (let's call it pair C), near the point that joins the three basins.

Drawing a line that joins pair A (Sideral and Cuncos) with Almendres, then drawing another that joins pair B (Tojal and Casas de Baixo) with pair C (Portela de Mogos and Maria do Meio) you will have that (1) the S. Sebastião menhirs are at the crossing, (2) one of the lines points to northermost moon set (+19 deg)at lesser standstill and, of course, southernmost moon rise (-19 deg) and (3) the other line points at sunset at winter solstice on the West side (-24 deg), and the Evoramonte hilltop and sunrise in summer solstice on the East side (+24 deg). The first line goes along the water-diving ridges, the other continues it - at S. Sebastião, it "bends". In my view, the astronomical problem is that none can see each other.

Finally, there's the consistent orientation of the antas' opening. It goes from 85 deg to 110 deg, to be more precise, 99 deg with a 10 deg standard deviation, in 91 7-stone antas (Hoskin and Calado, 1998). That means that 66% open in the interval 89-109 degrees.

As the result of work done in late 2001, Bob Holdam suggests that this orientation would point to the rise of the Pleiades seven-star constellation (one star, one upright stone), although he obtained a different value for the orientation (100-110 deg.). The Pleiades would be rising at 110 deg 7300 year ago, and at 100 deg 1500 years later.

In their 2005 web-paper, Marciano and Calado suggest that there is a good adherence to the hypothesis that it would point to the rise of the first full moon after spring equinox. That's the first full moon to rise south of where the sun rose that day, and a easy to observe indication of spring, not forgiving that the day before full moon, the rising moon calls one's attention. Although they shied from it, I must note that current western Easter is based upon the first full moon after equinox :"the Sunday immediately following the (Paschal) Full Moon that [falls] on or after the vernal equinox [...]. The church also ordered that if this Full Moon fell on a Sunday, the festival should be held seven days later." (Britannica "Calendar" entry, "The date of Easter; epacts".

Alright, that's it for the translations for now. I would like to say that's all, but of course it isn't. I must say, though, that all errors and imprecisions here are mine, not the original authors; and that no, I don't know enough to sustain a discussion. And sorry for the less than perfect English
:-)

Contributor Bio for Magalhaes: I was always puzzled by megaliths.

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