This led to further examination of similar potential alignments and, before long, a number were found radiating from St Michael's Mount. Three in particular were clearly powerful ones:
- alignment 108 went from Carn Brea near Camborne (a neolithic tor enclosure), through St Michael's Mount, then through the Merry Maidens stone circle, ending at Treryn Dinas, a spectacular cliff sanctuary near Porthcurno - two cliff sanctuaries, one tor enclosure and one stone circle);
- alignment 59 went from St Michael's Mount through Trencrom Hill to St Ives' Head (aka Pen Dinas, another cliff sanctuary, signs of which are now mostly obliterated) - two cliff sanctuaries and one tor enclosure;
- alignment 78 went from St Michael's Mount to Ennis Farm menhir and Boscawen-ûn stone circle (south side), proceeding to Maen Castle, another cliff sanctuary, then to the offshore Longships rocks. Then it proceeded over the sea to Chapel Downs cairns on St Martin's in the Isles of Scilly, finishing at South Hill, Bryher, one of the Scillies' more noteworthy sites. Yet another remarkable alignment, comprising two cliff sanctuaries, one stone circle, a cairnfield and a prominent hill on Bryher.
Something was going on. This discovery led to a more systematic examination of prominent natural features - hills and headlands. What emerged was that certain sites usually not recognised as cliff sanctuaries indeed could be so - Cape Cornwall, Pendeen Watch, Tol-pedn-Penwith (Gwennap Head) and St Ives' Head. This could be seen by the magnitude of alignments passing through them. All of these have since been confirmed as cliff sanctuaries (thanks, Craig Weatherhill).
More revealed itself. To wit: the major megalithic sites of Penwith were clearly located where they were by using this framework of alignments. This was a significant discovery.
Take, for example, alignment 80, which starts at Carn Brea, passing through an iron age enclosure at The Hood in East Penwith before hitting Trencrom Hill. Then it passes exactly through Lanyon Quoit and Boswens menhir before intersecting a cairn in the Tregeseal complex (Botallack Common), ending at the Brisons, some offshore rocks just off Cape Cornwall. This alignment was clearly a key factor in placing the Tregeseal complex where it is.
Some of these alignments would not normally be acceptable to geomancers - alignment 103 passes through only three sites. Geomancers avoid such three-point alignments, regarding them as inconclusive.
But this alignment is self-evident because of the magnitude of the three sites located on it: St Michael's Mount, Lanyon Quoit and Pendeen Watch. This, plus alignment 80 above, demonstrate how Lanyon Quoit was located where it now stands. It was put there as a node in a larger pattern of alignments.
Look at alignment 37: it starts at Treryn Dinas cliff castle, passing through Boscawen-ûn stone circle, Goldherring 2 Barrow, Newham Farm menhir (near Sancreed Well), then through Lanyon Quoit and Bosiliack Barrow (a neolithic chambered barrow), finally ending at Nine Maidens NW menhir (part of the Nine Maidens complex). So Lanyon Quoit is located at the intersection of 103, 80 and 37, and that's why it's there.
It's worth noting that major alignments don't always go straight to stone circles. Sometimes they go instead to outlying menhirs or cairns that are part of a stone circle complex - as with alignments 37 and 80 above. This shows how a complex as a whole is important, not just the stone circle in isolation.
Sometimes a major alignment goes straight through a stone circle. Alignment 108, mentioned above, passes through the Merry Maidens. Boscawen-ûn is placed at its precise location at the intersection of alignments 97, 78 (both going to the Scillies) and 79, 93 and 37 (all connecting with cliff sanctuaries).
Cape Cornwall has at least five backbone alignments going to it or through it. Trencrom Hill is visited by four. Botrea Barrows, visually unimpressive in their current state, act as a node for four backbone alignments.
So what are backbone alignments?
They are major alignments with a larger-than-local significance, as if they form the main 'circuitry' of an area like West Penwith.
How are these alignments decided upon? Well, generally they must pass through at least three major sites, with at least one of them being a significant natural feature (such as a hill or cliff sanctuary) and the other being a stone circle, quoit or a menhir, cairn or barrow.
Moreover, they must look right
as a backbone alignment. How this is defined is difficult to specify - it's a judgement call - but the backbone alignments map
shows good examples.
What is their significance? 'Backbone' is an internet-technology term, referring to the main fibre-optic 'pipes' connecting nations and regions to each other - in distinction to local circuits and distributary branches of the system.
They're analogous to high-tension power cables on the national grid, operating at a high voltage to reduce energy-loss over long distances. This power must be transformed to a lower voltage to enter local distribution networks. So backbone lines don't necessarily have a large number of points.
It might also be argued that cairns and menhirs that are part of a complex around a stone circle act as buffers, fuses or voltage-regulators for the stone circle complex as a whole.
However, remember that these are but analogies - they don't sufficiently explain how or why the system works.