152
In the early 1980s, 97 recumbent stone circles (RSC) in Aberdeenshire, Scotland
were examined for their orientations, astronomical declinations and the character of
the skyline as indicated by horizon scans (Ruggles, 1984b). Except for two, the
landscape settings are either on flat ground, hill tops, or south to south-east facing
slopes. Four horizon range categories were used by Ruggles (Fraser used three) to
evaluate skyline distances surrounding each RSC. Azimuths of the junctions
between each distance category were recorded to the nearest degree. A graph of that
data shows the x-axis as azimuth and the y-axis as a percentage of horizons by category (Ruggles, 1984b, Fig. 1). The obvious and general trend in that data indicates
a distinct preference for avoidance of horizons categorised as ‘near’ towards the
south. Ruggles also found ‘no convincing evidence that there existed a preference
for very distant, as opposed to moderately distant, horizons in any particular
direction’.
The horizon was similarly investigated in two studies of Bronze Age rock art
sites undertaken by the archaeologist Richard Bradley. The first, of petroglyphs in
Northumberland, England, found that the inscribed panels were carefully located at
viewpoints overlooking important prehistoric routes (Bradley, Harding, Rippon, &
Mathews, 1993). In each case, the extent of visibility was recorded in three distance
bands delimited by compass bearings—Restricted (<500 m), Intermediate
(500 m–5 km) and Distant (>5 km). Bradley applied the same method to analyse
vistas surrounding rock art panels in Galloway, south-west Scotland (Bradley,
Harding, & Mathews, 1993) with statistically supported correlations between
topography, aspect and preference/avoidance of horizons in particular distance
bands as categorised above.
Turning now to the Irish passage tombs, Fraser’s methodology is adopted here to
investigate the horizon surrounding each of these monuments at an island scale. The
aim is to test the data for evidence of orientated visibility of the horizon being correlated with a specific distance band (Restricted, Intermediate and Distant) and to
interpret the findings.
4 Horizon Scans at Irish Passage Tombs
The majority of Irish passage tombs occur mostly in the northern half of the island.
The distribution pattern is irregular, strongly characterised by dense or dispersed
clustering, and with a discernible preference for elevated siting as earlier described.
The inclusion of 36 unclassified hilltop cairns in the analysis is justified because of
their proximity to passage tombs in some cases or because these structures, if isolated, are often found to be targeted in an alignment sense by the passage and
entrance of a passage tomb facing a cairn (Prendergast, 2016).
Methodologically, horizon scans to measure notable changes in distance category by orientation were recorded at the sites shown in Fig. 2a. The technique
described below was used because of its speed and simplicity while simultaneously undertaking archaeoastronomical surveys at the tombs. Horizon scans can be
F. Prendergast
In the early 1980s, 97 recumbent stone circles (RSC) in Aberdeenshire, Scotland
were examined for their orientations, astronomical declinations and the character of
the skyline as indicated by horizon scans (Ruggles, 1984b). Except for two, the
landscape settings are either on flat ground, hill tops, or south to south-east facing
slopes. Four horizon range categories were used by Ruggles (Fraser used three) to
evaluate skyline distances surrounding each RSC. Azimuths of the junctions
between each distance category were recorded to the nearest degree. A graph of that
data shows the x-axis as azimuth and the y-axis as a percentage of horizons by category (Ruggles, 1984b, Fig. 1). The obvious and general trend in that data indicates
a distinct preference for avoidance of horizons categorised as ‘near’ towards the
south. Ruggles also found ‘no convincing evidence that there existed a preference
for very distant, as opposed to moderately distant, horizons in any particular
direction’.
The horizon was similarly investigated in two studies of Bronze Age rock art
sites undertaken by the archaeologist Richard Bradley. The first, of petroglyphs in
Northumberland, England, found that the inscribed panels were carefully located at
viewpoints overlooking important prehistoric routes (Bradley, Harding, Rippon, &
Mathews, 1993). In each case, the extent of visibility was recorded in three distance
bands delimited by compass bearings—Restricted (<500 m), Intermediate
(500 m–5 km) and Distant (>5 km). Bradley applied the same method to analyse
vistas surrounding rock art panels in Galloway, south-west Scotland (Bradley,
Harding, & Mathews, 1993) with statistically supported correlations between
topography, aspect and preference/avoidance of horizons in particular distance
bands as categorised above.
Turning now to the Irish passage tombs, Fraser’s methodology is adopted here to
investigate the horizon surrounding each of these monuments at an island scale. The
aim is to test the data for evidence of orientated visibility of the horizon being correlated with a specific distance band (Restricted, Intermediate and Distant) and to
interpret the findings.
4 Horizon Scans at Irish Passage Tombs
The majority of Irish passage tombs occur mostly in the northern half of the island.
The distribution pattern is irregular, strongly characterised by dense or dispersed
clustering, and with a discernible preference for elevated siting as earlier described.
The inclusion of 36 unclassified hilltop cairns in the analysis is justified because of
their proximity to passage tombs in some cases or because these structures, if isolated, are often found to be targeted in an alignment sense by the passage and
entrance of a passage tomb facing a cairn (Prendergast, 2016).
Methodologically, horizon scans to measure notable changes in distance category by orientation were recorded at the sites shown in Fig. 2a. The technique
described below was used because of its speed and simplicity while simultaneously undertaking archaeoastronomical surveys at the tombs. Horizon scans can be
F. Prendergast