With a number of hunebedden the gaps between the side stones at the opposite sides make a kind of ’underpasses’, which support an orientation. To what extend an orientation grid forms the basis of it is unknown. In such a case the underpasses should have orientations mainly, that agree with the orientation lines of a grid (see the page Orientation grid). Four types of underpasses are distinguished on this page: diagonal through the hunebed, straight to the opposite side and left and right to the opposite side.
Of every underpass the orientation was determined via three measurements: through the midst of two side stones and left and right along the side stones. A sounding compass (fault ±0.3°) was used for this task. The average of the three measurements gives the orientation of the underpass. Only underpasses, where the orientation lines run free through the gaps at each opposite side are taken into account. It has not been reckoned with the subsiding of stones nor with possible restorations. Therefore fitting values could deviate from or diverging values could accidently fit to a sudden pattern.
In the diagrams below dotted lines are used for values, which come from the various orientation grids. (See the page Orientation grid for this.) Those are: 0°, 9°, 13°, 18°, 117°, 140°, 143°, 162°, 167° and 171° (green) and at a right angle to them: 90°, 103°, 108°, 27°, 50°, 53°, 72°, 77° and 81° (blue).
Four outstanding clusters in the diagrams for the measurements left and right to the opposite sides (dotted red) don’t match the orientation of any grid. It touches upon the azimuth values of 33° / 122° and 39° / 129°. The values 33° and 39° are measured via the left and the values 122° and 129° via the right opposite side. Since those pairs diverge 90° from each other, it seems obvious to suppose another still unknown construction in a grid.
It shouldn’t surprise, that the values of the diagonal measurements and the measurements straight across lie in mutual exclusive ranges. After all the diagonals represent the longitudinal and the lines across the transverse direction of the hunebed more or less. Only both measurements with values close to 80° are out of place. But that such mutual exclusive ranges occur for the measurements to the left and right of the opposite sides, can be called strikingly.
The measurements to the left give values above 90° mainly and those to the right below 90°. The anomalies to the right concern D23 with its longitudinal axis at ±77° and D30 at ±167°. To the right they are: D19 at ±117°, D24 at ±68°, D30 at ±167° and D32 at ±69° [15.1]. Due to the spread of orientations of the longitudinal axes, the anomalies cannot be explained by them. But a specific way of orientating can have played a role here: 77° and 167° stand at a right angle to each other, while 68° and 69° have almost the same orientation.
In order to find out which orientations don’t have apexes and the other way around if unexpected apexes occur, all measurements have been put together in one diagram. Orange circles demonstrate the extra apexes, while with the red crosses an apex apears to fail. But one should be careful at this point. The disturbance of hunebedden can have resulted in deviating values and the missing apexes could be ascribed to the low number of measurements.
Except for the mentioned clusters, the next values fail: 53°, 72°, 90° 140° and 167°. With the values of 77° and 81° the situation is unclear. Additional apexes are found with 5°, 55°-60°, 87°, 111°, 145°-158°, 176° and maybe 165°. Of those 87° and 176° stand at a right angle, which perhaps can be the case for the intervals of 55°-60° and 145°-158° too. Furthermore the very width apex at 27° stands out. Maybe it results from the merging of several apexes.
The most striking phenomenon is the separation at 90° of the measurements through the underpasses to the left and right. Because of the spread of orientations of the longitudinal axes of the concerning hunebedden, this separation cannot flow from the measuring method. As strikingly is the absence of 90° itself as an orientation of an underpass. Because of the low number of measured hunebedden, it’s premature to draw conclusions at this moment.
Giving the fact, that with a low number of measured hunebedden quite a lot of additional apexes are found already, one can conclude that:
- the orientation of the underpasses can’t be explained by an orientation grid all the time and/or
- the presentation of orientation grids on the page Orientation grid is incomplete yet.