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Measurements on Dutch passage mounds

(One of?) the first web pages on Dutch megalithic passage mounds (since beginning 1996)

Orientation measurements

From this picture one can deduct that most chambers are oriented between 246^o and 305^o (75% of measured passage mounds). The main declination will be between: -14^o and 20^o. The declination is not really dependent on the altitude of the horizon, because in this region of The Netherlands the horizon could be at maximum some 10 [m] lower than at the location of the passage mound (or the effect of trees had to be significant in the past).

Comparable orientations can be found on the German passage mounds (of the same time frame, 3300 BCE to 2600 BCE, close together [100 km], and comparable cultural environment [Funnel Beaker Culture]). 

Possible explanation for this distribution

I have the following theory that the deviation has to do with the full moon positions around equinox at building time of the mounds:

• The deviation of the Dutch passage mounds is around 270° or 90°, so a relation with equinox (my definition of equinox is that sun sets or rises at 270° or 90°: around March 18^th, 1999 AD) could have some significance
• The main reason why I think that it is not equinox that former people were interested in, is because it is not a very interesting day in many cultures. Perhaps a full moon setting before or after equinox is much more appropriate for a rite!
• Furthermore and more important: I don't think it is equinox itself, because there are clusters of mounds standing very close to each other (up to three within 50 m), which still vary in the orientation of the main axis by a few degrees.
• Related to something like easter (Christian calendar)?

Easter Sunday is to be the first Sunday after the first full moon after the 21th of March (spring equinox). If this full moon falls on a Sunday, it is to be the following Sunday.
For calculations of Easter sunday; see here.
But I have the idea that the megalithic people also looked after autumn equinox (or before spring equinox), because the distribution is not one sided around 270° or 90°.
• Related to Harvest Moon (full moon closest to autumn equinox)?
• The altitude of the horizon could be of influence, but the height differences in the Netherlands are not very large (in Niedersachen, where 53 mounds were measured, the horizon has more height differences). It could be that the height of the trees in the surroundings is important... Difficult to determine.
• The max. difference between sunset (or sunrise) azimuths some 29 days (the moon's orbit time) before and after equinox is around 2 * 17°.
  If you include the max. moon set/rise difference due to its inclination/perturbation, the moon's azimuth before and after equinox can vary around 2 * 17° + 2 * 9° (at a latitude 53°) = 52°. In the below picture the moon's azimuth is determined from its actual (ephemeris) moon sets in the time period 29 days before/after equinox.
  
This 52° is thus comparable to the 2*25° measured orientation of the passage mounds!
• The question is, if we calculate the full moon set (or rise) azimuths around equinox, do we get a comparable distribution of orientations as actually measured with the passage mounds?
  Here is the distribution of calculated full moon setting between 1999-2092 AD (5 times the nodal cycle) before and after spring equinox (calculated with the help of the JPL's HORIZONS ephemeris) and the distribution of the orientation of the passage mounds in The Netherlands and Germany:

• The interval width of this distribution is 10°, because according to normal statistical practice an interval should hold at least 5 to 10 sample . Because the number of passage mounds in the Netherlands is 54, and the distribution spans some 60° (from 250° - 310°), the interval width should be at least 6°. So the chosen interval of 10° seems to be oke.
  This interval value will thus obscure any perturbation/etc. effects of the moon's orbit and also most inaccuracies of the measured orientation (1 sigma around 1°).
• The distributions look comparable, but if using the Kolmogorov-Smirnov test (Dn*) it looks as if the orientations of the NL and DE passage mounds don't have the same distribution as the azimuths of the full moon setting around equinox.

• When using the Chi-Square test (5 intervals [4 degrees of freedom] to keep the number of samples per interval > 5) for both the NL and the DE passage mounds the hypothesis (that the distribution of azimuths of the passage mounds is equal to the full moons azimuths around equinox) is rejected (99%).

Other possible explanations

• Other locations where similar alignments are found at Armenoi, Crete
• Dig mound by eye (Keith Pickering)
  How about:
1. Ancient cultural requirement to orient mound passage E-W for religious reasons;
2. But (unlike our own culture) little cultural interest in actually measuring things.
3. So you dig the mound with an east-west orientation, as determined roughly by eye.
About 25 degrees of scatter seems about right.
Remark VR: Could be indeed.
• The orientation could be towards any planet, because any planet/moon on the ecliptic gives the same orientation variation as shown above.
  Remark VR: Not true, there is still this +/-25° distribution. So equinox itself was important. Furthermore I think the moon is more important in most cultures then e.g. Venus or Jupiter. And full moon is a very distinct feature in the sky, which has been an important factor in a lot of cultures.

Spliced stones

Spliced stones at D25

• cover stones 1 and 2
  A lot of points on cover stones 1 and 2 provide evidence of the splitting. One of these evidences can be seen in the below pictures.
  
The scale and angle of the two pictures is different! Furthermore: the brownish is the flat face of the stone while the greenish part is the vertical step.


A step in the underside of cover stone 1


A step in the underside of cover stone 2


• cover stones 3 and 4

First we see two pictures of a three sided pyramid on the undersides of cover stone 3 and 4. On stone 3 the pyramid comes out of the stone and at cover stone 4 is thus goes inward.

Outward 3 sided pyramid on cover stone 3


Inward 3 sided pyramid on cover stone 4

In the following picture one sees the superposition of the two pictures:

Superposition of pyramid 3 (brownish) with pyramid 4 (bluish)

Spliced stones at D29

More specific geometry info:

side	stone 1	stone 2
#	[mm]	[mm]
1	1200	1100
2	1700	1750
3	1000	1140
4	2000	1800
5	700	860
6	1660	1700
	====	====
Total	8260	8350

Possible methods to split stones

• just by coincidence (perhaps because of frost/water/etc.). An example has been seen in Ireland, Co. Wicklow.
• people pushed them over a hill lock. There are not many of them in The Netherlands;-), so this I would rule this out.
• They used fire. An even split could be made by put a burnable string of some material (palm e.g.) around the rock, burn this material and then pour water over it. The stone could split just a the 'circle' where the material was.
• they used wooden pegs to split the stone (like we still do with iron pegs). Would that be feasible on gneiss and granite?
• usage of wooden poles in round holes. By making the poles wet, the stone splits (practice in Greece and Italy).
• use little interstices, filling them with water, and allowing them to crack due to frost (with the aid of wooden poles and so on).
• by laser, but I don't think the people at that time will have had this and the surface is not regular enough to support this.
• using cleavage, which is a predictable way splitting occurs. At least it was predictable to the ancient masons. It may be relevant to recall the Danish scientist Steno who, in the 1600's announced the 'law of constancy of interfacial angles', which observed that no matter how large or small, narrow or thick, the angles of quartz prism faces remained constant... always 60 degrees.
• The slight variations observed on sites just 50m away from one another indicates a "processional " and that the event was "probably" tracked on foot between sites by the people who built them (Dutch Neolithic Beaker culture) so that the entire sunrise and possibly  sunset and (as here suggested) full moon or even eclipse track could be observed, prayed to, offered to, worshipped etc. The sequence would depend upon which end allows the aperture (opening).
• your idea! Please send them to me!

Links to other sites

• Passage mounds in the Netherlands (a lot of pictures)
• Azimuth measurements of German passage mounds

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