Creag Na Cailliche

David Dorren and Nina Henry

A single massive standing stone is in woodland at NS 09560 70692 c20m inland from the minor road that runs along the E shore of Loch Striven and c30m from the shore itself. Loch

Striven is a sea loch that runs roughly N/S at the latitude of the stone, which is near the entrance to the loch at its S end. Across the loch to the W is a range of hills rising gently from Strone Point at the S end to the broad summit of Meallan Sidhein (449m, NS 06233 74484), the highest point visible from the standing stone.

The presence of the standing stone has been noted in Canmore (ID 40470), but it is not described. It is near the feature marked on OS maps as Creag na Cailliche which gives the Canmore site its name. The OS Name Book entry for Creag na Cailliche refers to “a remarkable stone” located on the S end of the rocks on the Loch Striven shore, and “the subject of a superstitious tradition which bequeaths to the Craig its name, The Old Woman’s or Witch’s Craig”. In an additional note the stone is identified as a glacial boulder. It is marked on the 6" maps and on modern maps. We located the stone, a glacial erratic, on the rocks on the shore at NS 09521 70594. It is not the standing stone, which is not mentioned in the Name Book and is not marked on the OS 6" map Argyllshire CXCIV, surveyed 1864–5, or on the 1915 revision, or later OS maps.

The standing stone is c100m NNE of the Creag na Cailliche boulder. It is on the W edge of a slightly elevated grassy flat area with several large boulders nearby. It is c2.4m tall and 0.7–0.8m thick. There is a significant difference between the two opposite broad faces, which are in the NW and SE directions approximately. One face is fairly flat and points in the general direction of the summit of the hill across the loch, roughly NW. The opposite SE face is much more lumpy and irregular. The NW flat face is narrow at the top, with a maximum width of 1.4m halfway down, narrowing to 1.2m at the base. The stone leans NW in the direction of the flat face at an angle of about 28° to the vertical, supported by a natural rock outcrop on the NW side at its base. This outcrop is 0.65m high, 1.8m wide across the front of the stone, and 0.2m wide in the NW direction. The SE side of the standing stone has a short narrow linear open cavity resembling an exposed drill hole, but its line is similar to quartz veins in the stone and it may be one that has been weathered out.

The orientation of the stone suggested a possible alignment to the setting point of the sun at the Summer Solstice (SS), around June 21, if that occurred on the opposite hilltop. The location of the setting point can be calculated, and that was done for the present epoch in advance of the 2018 solstice, since adverse weather might have prevented verification by direct observation. Moreover, if the stone is prehistoric, the setting point would have been different at an earlier epoch, as a result of the very slow change in the inclination of the Earth’s axis (the obliquity of the ecliptic), and the setting point for earlier epochs can also be calculated to determine the displacement from its present position. The calculation is outlined here. The azimuth of setting of the sun (the angle measured clockwise from the N point) at any location is determined by two quantities: the latitude of the observing location and the declination of the sun, which is the angle of the sun above or below the celestial equator (the plane of the earth’s equator). The latitude of the stone obtained from the GPS measured position is 55°.89. At the Summer Solstice the sun’s declination is at its maximum, taken to be currently +23°.44. (the tilt of the Earth’s axis). It is then a standard and straightforward calculation of spherical trigonometry to obtain the azimuth of setting on the horizon at the Solstice. The result is 315°.2, or essentially NW. However, at the location of the stone the sun sets on the hillside across the loch, not on the horizon. Since we do not know a priori the height of the hill at the setting point the calculation of the setting point on the hillside is an estimate to within a few degrees. (Note that at the other extreme of the Sun’s declination, -23°.44 at the Winter Solstice, the setting point is 90° farther S, over the Isle of Bute.) For a hill height of 450m, the height of Meallan Sidhein, and a distance of c5km (from the map), the azimuth of setting on the hilltop was calculated to be c308°, which is c8° to the S of the summit, or to its left, viewed from the stone. Lowering the height to 400m makes only a small change to the position, to c7° left of the summit.

If the stone is prehistoric, the obliquity of the ecliptic differed at that epoch from the present value of 23°.44. Taking 3,000 BC (in the Neolithic) as an example, a modern calculation has given the obliquity at that epoch as 24°. However, recalculation using this value for the maximum solar declination gives the azimuth of setting on the horizon as 316°.5, only a small shift of 1°.3 from the calculated value of 315°.2 for the present. At that epoch the setting point would still have been to the left of the summit, by c6°–7°.

Fortunately, a direct observation of the SS sunset on June 22, 2018 was possible. This was one day after the precise time of the SS, but the solar declination is at a standstill for a few days around the SS, so this is the solsitial observation. Its position was photographed and also marked on a previous photo. The sun was observed to set a few degrees to the left of the summit near a notch on the hillside formed by the nearer and lower hill Meallan Glaic (404m, NS 06685 73136), whose slope seen against the background hillside creates the notch. From the map, the angle between the notch and the hilltop is estimated to be c5°, so that the observed setting point is c5°left of the summit, and there is thus rough agreement between observed and calculated positions. The sun does not set on the summit, nor would it have 5,000 years ago.

The stone is located at a point from which the Summer Solstice sunset is observed to occur nearer the notch rather than the hill summit and would have done so at a much earlier epoch. It raises the possibility that this location has been chosen because the notch is a more precise marker than the broader hilltop, the stone indicating the general direction of the solstitial setting. This work was undertaken on 24 April, 15 May, 22 June and 26 June 2018.

(Source: DES, Volume 19)